the present invention relates to methods and compositions for treating autoimmune diseases , and in particular for treating rheumatoid arthritis with sphingomyelin pathway inhibitors . the description of the invention that follows discusses i ) fas - mediated apoptosis , ii ) apoptosis and the immune system , iii ) reversing the resistance to apoptosis as a treatment of autoimmune disease . iv ) formulation of inhibitors of the sphingomyelin pathway , and v ) delivery of formulations and intra - articular injections . homeostasis of mammalian tissues is controlled not only by proliferation and differentiation of cells , but also by cell death . there are two death processes , apoptosis and necrosis . the death of cells during embryogenesis , metamorphosis , endocrine - dependent tissue atrophy , and normal tissue turnover is called programmed cell death . most of the programmed cell death which occurs during mammalian development proceeds by apoptosis . apoptosis can be distinguished morphologically and biochemically from necrosis . necrosis occurs during pathological cell death as a result of injury , complement attack , severe hypoxia , hyperthermia , lytic viral infection , and exposure to a variety of toxins . apoptosis is accompanied by condensation and segmentation of nuclei , loss of plasma membrane microvilli , and extensive degradation of the chromosomal dna into nucleosome units . it is believed that the apoptotic signal is induced by the binding , of the fas ligand to fas . see generally , s . nagata . “ fas and fas ligand : a death factor and its receptor .” advances in immunology 57 : 129 ( 1994 ). the cytoplasmic domain of fas consists of 145 amino acids . about 70 amino acids in this region have significant similarity with a part of the cytoplasmic region of the type i ( but not type ii ) tnf receptor . indeed , analyses of point mutations in the fas protein in this conserved region have shown that the domain is essential for the function of fas . the fas ligand has been identified , isolated , and cloned . the amino acid sequence deduced from the nucleotide sequence of the cdna indicates that the fas ligand is a tnf - related type ii membrane protein . however , despite the high similarity between fas ligand and tnf ( about 30 % identical at the amino acid sequence level ). fas ligand does not bind to the tnf receptor . the tissue distribution of fas mrna in the mouse has been examined . fas mrna can be detected abundantly in the thymus , heart , liver , and ovary of 8 - week old mice , but not in the brain , bone marrow , and spleen . fas is expressed in almost all populations of thymocytes . this , wide distribution of fas is in sharp contrast to the tissue restrictive expression of fas ligand ; fas ligand is found on the sertoli cells of the testis , on the corneal epithelium , iris and retina , and on activated t lymphocytes . the activation of fas is caused by aggregation mediated by the fas ligand ( or other agonist , such as antibodies ). the signal is thought to be transduced by clustering of the intracellular domain . the downstream elements of the apoptosis process are thought to be affected by the sphingomyelin signal transduction pathway . see generally ,. r . n . kolesnick et al ., “ the sphingomyelin signal transduction pathway mediates apoptosis for tumor necrosis factor , fas , and ionizing radiation ,” biochem . cell biol . 72 : 471 ( 1994 ). this pathway is initiated by enzymatic hydrolysis of the phosphodiester bond of sphingomyelin by a specific sphingomyelin - directed phospholipase c (“ sphingomyelinase ”), generating ceramide and phosphocholine . ceramide serves as the second messenger of the pathway , initiating signaling for several biological agents . ultimately , ceramide activates the death signaling pathway in a jun kinase ( jnk )- mediated pathway . see m . verheij et al ., “ requirement for ceramide - initiated sapk / jnk signaling in stress - induced apoptosis ,” nature 380 : 75 ( 1996 ). ceramide , however , can also be metabolized to sphingosine and sphingosine - 1 - phosphate ( spp ) by the action of ceramidase and sphingosine kinase , respectively . see generally c . j . van koppen et al ., “ activation of a high affinity g i protein - coupled plasma membrane receptor by sphingosine - 1 - phosphate ,” j . biol . chem . 217 : 2082 ( 1996 ). spp has been shown to be involved in stimulating dna synthesis and cell division , i . e ., proliferation . importantly , spp has been recently shown to inhibit fas - mediated cell death . see o . cuvillier et al ., “ suppression of ceramide - mediated programmed cell death by sphingosine - 1 - phosphate ,” nature 381 : 800 ( 199 ). the principal physiologic function of the immune system is the elimination of infectious organisms . the effector mechanisms that are responsible for protective immunity are also capable of injuring host tissues . in some situations , specific immune responses have little or no protective value , and the harmful consequences become dominant . the best example of this is autoimmune disease caused by pathologic immune responses against self - antigents . the immune system has evolved multiple mechanisms for controlling potentially harmful reactions . failure of these mechanisms may lead to tissue injury and disease . potentially harmful immune reactions may be prevented either by functionally inactivating or killing the responding lymphocytes . the primary cytolytic mechanism involved in controlling lymphocyte responses is the fas - mediated apoptotic pathway discussed above . in this manner , the immune system actively eliminates potentially harmful cells so that the host may survive . see a . abbas , “ die and let live : eliminating dangerous lymphocytes .” cell 84 : 655 ( 1996 ). the mechanism by which fas - fas ligand interactions maintain immunological tolerance to self - antigens is yet to be completely understood . it is believed that repeated stimulation of antigen cause t cells to express high levels of fas and fas ligand , thereby killing either themselves or one another . such a homeostatic mechanism may limit the size of lymphocyte clones responding to foreign antigens . the same mechanism may be triggered by abundant and disseminated self - antigens , which are able to interact repeatedly with specific t cells . abnormalities in fas - mediated cell death pathways may result in autoimmunity even in situations in which fas and fas ligand are themselves normal , for example , where apoptosis is inhibited and a proliferation pathway is stimulated , activated lymphocytes may escape elimination and cause disease . the present invention contemplates reversing the resistance to apoptosis by inhibiting downstream events of the sphingomyelin pathway . in this manner , activated lymphocytes go through the apoptosis pathway and are eliminated . it is believed that such treatment of ra patients will reduce the symptoms that are characteristic of ra . iii . reversing the resistance to apoptosis as a treatment of autoimmune disease it is not intended that the present invention be limited to particular points in the sphingomyelin pathway or particular inhibitors of the sphingomyelin pathway . as noted above , spp has been recently shown to inhibit the fas - mediated cell death pathway . while , the present invention contemplates inhibiting spp , thereby reversing the inhibition of fas - mediated apoptosis , the present invention also contemplates inhibiting the sphingomyelin pathway at other points . fig1 is a schematic showing the broad nature of the targets contemplated for therapeutic intervention in ra . as shown in fig1 ( and discussed above ), following fas ligation , sphingomyelin is converted to ceramide through the activation of acid sphingomyelinase . ceramide activates the death signaling pathway in a jun kinase ( jnk )- mediated pathway . through its inhibitory effect on erk 1 / 2 , ceramide can also block proliferation , thus shifting the balance further toward apoptosis . since increased levels of ceramide may promote programmed cell death , in one embodiment , the present invention contemplates treatment of ra patients with inhibitors of ceramide catabolism . it is not intended that the present invention be limited by the nature of the inhibitor . in one embodiment , the present invention contemplates inhibiting ceramide catabolism by inhibiting its conversion to free sphingosine by ceramidase [ e . g ., by using n - oleoylethanolamine , ( 1s , 2r )- d - erythro - 2 -( n - myristoylamino )- phenyl - 1 - propanol (“ d - mapp ”) or other suitable inhibitor ]. in another embodiment , the present invention contemplates inhibiting ceramide catabolism by inhibiting metabolism to glucosylceramide by glucosylceramide synthase [ e . g ., by using d - threo - 1 - phenyl - 2 - decanoylamino - 3 - morpholino - 1 - propanol (“ pdmp ”) and newer homologues or by using n - butyldeoxynojirimycin or other suitable inhibitors ]. in yet another embodiment , the present invention contemplates inhibiting ceramide catabolism by inhibiting metabolism to sphingomyelin by sphingomyelin synthase or by inhibiting metabolism to ceramide - 1 - phosphate by ceramide kinase . in still another embodiment , the present invention contemplates inhibiting ceramide catabolism by inhibiting metabolism to 1 - o - acylceramide by ceramide transacylase ( e . g . by using d - and l - erythro enantiomers of pdmp and related homologues ). on the other hand , as discussed above . spp has an antagonistic effect to that of ceramide . it is produced from sphingosine by the activity of sphingosine kinase . it has a dual , gi - protein - dependent , anti - apoptotic effect . it blocks jnk activation on the one hand , and leads to erk 1 / 2 activation on the other . thus , the net effect of spp is inhibition of ceramide - mediated cell death . while it is not intended that the present invention be limited to a precise understanding of the mechanism , it is believed that resistance to fas - mediated cell death in ra is due to a shift in the ceramide / spp rheostat . suppressing the pathway ( e . g . by suppressing spp synthesis with a sphingosine kinase inhibitor , or blocking its gi - mediated effects ) can both restore the susceptibility of ra lymphocytes to killing by fas ligation . accordingly , targets for therapeutic intervention in ra include ( but are not limited to ) inhibition of sphingosine kinase , inhibition of gi proteins , inhibition of mek1 , activation of jnk , or a combination of two or more of those modalities . in one embodiment , the present invention contemplates treating ra patients with compounds that inhibit sphingosine - phosphate formation . while inhibition of sphingosine kinase ( e . g ., with sphingosine derivatives ) has been discussed , other approaches to inhibiting sphingosine phosphate formation are contemplated , including inhibiting ( 1 ) synthesis of long chain bases ( e . g . by use of β - chloroalanine or l - cycloserine or other suitable inhibitor ), ( 2 ) inhibition of acylation of long chain bases , a critical step in eventual sphingosine formation ( e . g . using fumonisin b1 or other suitable inhibitor ), and ( 3 ) stimulation of sphingosine - 1 - phosphate phosphatase or lyase . the present invention contemplates preparations comprising inhibitors of the sphingomyelin signal transduction pathway . such formulations can be prepared either as liquid solutions or suspensions , or in solid forms . formulations may include such normally employed additives such as binders , fillers , carriers , preservatives , stabilizing agents , emulsifiers , buffers and excipients as , for example , pharmaceutical grades of mannitol , lactose , starch , magnesium stearate , sodium saccharin , cellulose , magnesium carbonate , and the like . these compositions take the form of solutions , suspensions , tablets , pills , capsules , sustained release formulations , or powders , and typically contain 1 %- 95 % of active ingredient , preferably 2 %- 70 %. the compositions are also prepared as injectables , either as liquid solutions or suspensions ; solid forms suitable for solution in , or suspension in , liquid prior to injection may also be prepared . for intra - articular injections ( see below ), the present invention contemplates formulations comprising one or more inhibitors of the sphingomyeline pathway along with one or more local anesthetic . it is not intended that the present invention be limited to particular anesthetics . a variety are contemplated including but not limited to procaine or lidocaine . when injecting a bursa , tendon sheath , or periarticular region , such a mixture will give immediate relief ( due to the anesthetic ) followed by more lasting relief ( due to the inhibitor ). where mixtures with local anesthetics are not desired , a topical anesthetic prior to injection may be used . such topical anesthetics include but are not limited to ethyl chloride spray on the skin over the joint to be injected . alternatively , a local anesthetic may be given first , followed by administration of one or more of the above - described inhibitors . it is not intended that the present invention be limited to the particular route of administration . the sphingomyelin pathway inhibitors can be given orally or injected ( including but not limited to intravenous injection ). the present invention specifically contemplates intra - articular injections in ra patients . to perform an arthrocentesis , the specific area of the joint to be injected is palpated and is then marked , e . g ., with firm pressure by a ballpoint pen that has the inked portion retracted . this will leave an impression that will last 10 to 30 minutes . ( the ballpoint pen technique can also be used with soft tissue injection .) the area to be aspirated and / or injected should be carefully cleansed with a good antiseptic , such as one of the iodinated compounds . then the needle can be inserted through the ballpoint pen impression . helpful equipment includes the following items : alcohol sponges ; iodinated solution and surgical soap ; gauze dressings ( 2 × 2 ); sterile disposable 3 -, 10 - and 20 - ml syringes ; 18 - and 20 - gauge , 1½ - inch needles ; 20 - gauge spinal needles ; 25 - gauge , ⅝ - inch needles ; plain test tubes ; heparinized tubes ; clean microscope slides and coverslips ; heparin to add to heparinized tubes if a large amount of inflammatory fluid is to be placed in the tube ; fingernail polish to seal wet preparation ; chocolate agar plates or thayer - martin medium ; tryptic soy broth for most bacteria ; anaerobic transport medium ( replace periodically to keep culture media from becoming outdated ); tubes with fluoride for glucose ; plastic adhesive bandages ; ethyl chloride ; hemostat ; tourniquet for drawing of simultaneous blood samples ; and 1 percent lidocaine . the knee is the easiest joint to inject . the patient should be in a supine position with the knee fully extended . the puncture mark is made just posterior to the medial portion of the patella , and an 18 - to 20 - gauge , 1½ - inch needle directed slightly posteriorly and slightly inferiorly . the joint space should be entered readily . on occasion thickened synovium or villous projections may occlude the opening of the needle , and it may be necessary to rotate the needle to facilitate aspiration of the knee when using the medial approach . an infrapatellar plica , a vestigal structure that is also called the ligamentum mucosum , may prevent adequate aspiration of the knee when the medial approach is used . however , the plica should not adversely affect injections or aspirations from the lateral aspect . injections in the shoulder are most easily accomplished with the patient sitting and the shoulder externally rotated . a mark is made just medial to the head of the humerus and slightly inferiorly and laterally to the coracoid process . a 20 - to 22 - gauge , 1½ - inch needle is directed posteriorly and slightly superiorly and laterally . one should be able to feel the needle enter the joint space . if bone is hit , the operator should pull back and redirect the needle at a slightly different angle . the acromioclavicular joint mast be palpated as a groove at the lateral end of the clavicle just medial to the shoulder . a mark is made , and a 22 - to 25 - gauge . ⅝ to 1 - inch needle is carefully directed inferiorly . rarely is synovial fluid obtained . the sternoclavicular joint is most easily entered from a point directly anterior to the joint . caution is necessary to avoid a pneumotharax . the space is fibrocartilaginous , and rarely can fluid be aspirated . for injections of the inhibitors of the present invention in the ankle joints , the patient should be supine and the leg - foot angle at 90 degrees . a mark is made just medical to the tibialis anterior tendon and lateral to the medial malleolus . a 2 - to 22 - gauge , 1½ - inch needle is directed posteriorly and should enter the joint space easily without striking bone . again , the patient is supine and the leg - foot angle at 90 degrees . a mark is made just inferior to the tip of the lateral mallcolus . a 20 - to 22 - gauge , 1½ - inch needle is directed perpendicular to the mark . with this joint the needle may not enter the first time , and another attempt or two may be necessary . because of this and the associated pain , local anesthesia may be helpful . this is a complex joint , but fortunately most of the intercarpal spaces communicate . a mark is made just distal to the radius and just ulnar to the so - called anatomic snuff box . usually a 24 - to 26 - gauge , ⅝ to 1 - inch needle is adequate , and the injection is made perpendicular to the mark . if bone is hit , the needle should be pulled back and slightly redirected toward the thumb . degenerative arthritis often involves this joint . frequently the joint space is quite narrowed , and injections may be difficult and painful . a few simple maneuvers may make the injection fairly easy , however . the thumb is flexed across the palm toward the tip of the fifth finger . a mark is made at the base of the first metacarpal bone away from the border of the snuff box . a 22 - to 26 - gauge , ⅝ to 1 - inch needle is inserted at the mark and directed toward the proximal end of the fourth metacarpal . this approach avoids hitting the radial artery . synovitis in these joints usually causes the synovium to bulge dorsally , and a 24 - to 26 - gauge . ½ to ⅝ - inch needle can be inserted on the either side just under the extensor tendon mechanism . it is not necessary for the needle to be interposed between the articular surfaces . some prefer having the fingers slightly flexed when injecting the metacarpophalangeal joints . it is unusual to obtain synovial fluid . when injecting , a mix of the inhibitors of the present invention with a small amount of local anesthetic is preferred . the techniques are quite similar to those of the metacapophalangeal and finger interphalangeal joints , but many prefer to inject more dorsally and laterally to the extensor tendons . marking the area ( s ) to be injected is helpful as is gentle traction on the toe of each joint that is injected . a technique preferred by many is to have the elbow flexed at 90 degrees . the joint capsule will bulge if there is inflammation . a mark is made just below the lateral epicondyle of the humerus . a 22 - gauge , 1 to 1½ - inch is inserted at the mark and directed parallel to the shaft of the radius or directed perpendicular to the skin . this is a very difficult joint to inject even when using a fluoroscope as a guide . rarely is the physician quite sure that the joint has been entered ; synovial fluid is rarely obtained . two approaches can be used , anterior or lateral . a 20 - gauge , 3½ - inch spinal needle should be used for both approaches . for the anterior approach , the patient is supine and the extremity fully extended and externally rotated . a mark should be made about 2 to 3 cm below the anterior superior iliac spine and 2 to 3 cm lateral to the femoral pulse . the needle is inserted at a 60 degree angle to the skin and directed posteriorly and medially until bone is hit . the needle is withdrawn slightly , and possibly a drop or two of synovial fluid can be obtained , indicating entry into the joint space . many prefer the lateral approach because the needle can “ follow ” the femoral neck into the joint . the patient is supine , and the hips should be internally rotated the knees apart and toes touching . a mark is made just anterior to the greater trochanter , and the needle is inserted and directed medially and sightly cephalad toward a point slightly below the middle of the inguinal ligament . one may feel the tip of the needle slide into the joint . for injections , the tempormandibular joint is palpated as a depression just below the zygomatic arch and 1 to 2 cm anterior to the tragus . the depression is more easily palpated by having the patient open and close the mouth . a mark is made and , with the patient &# 39 ; s mouth open , a 22 - gauge , ½ to 1 - inch needle is inserted perpendicular to the skin and directed slightly posteriorly and superiorly . the following examples serve to illustrate certain preferred embodiments and aspects of the present invention and are not to be construed as limiting the scope thereof . in the experimental disclosure which follows , the following abbreviations apply : eq ( equivalents ); m ( molar ); μm ( micromolar ); n ( normal ); mol ( moles ); mmol ( millimoles ); μmol ( micromoles ); nmol ( nanomoles ); gm ( grams ); mg ( milligrams ); μg ( micrograms ); l . ( liters ); ml ( milliliters ); μl ( microliters ); cm ( centimeters ); mm ( millimeters ); μm ( micrometers ); nm ( nanometers ): ° c . ( degrees centigrade ); dms ( n , n - dimethylsphingosine ); erk [ extra - cellularly regulated kinase ( erk1 for the p44 mapk ; erk2 for the p42 mapk ; erk3 for the p63 mapk )]; mapk ( mitogen - activated protein kinase ) ( see generally , u . s . pat . nos . 5 , 663 , 313 and 5 , 663 , 314 , both of which are hereby incorporated by reference ); mapkk ( map kinase kinase ); mek ( mitogenically extraregulated kinase ); mekk ( me kinase kinase ); z - vad - fmk [ n - benzyloxycarbonyl - val - ala - asp ( o - methyl )- fluromethylketone ]. in some of the examples below , the tunel assay was used . tdt - mediated dutp - biotin nick end - labeling ( tunel ) assay was performed as described [ see ( gorczyca , w , et al . leukemia 7 , 659 - 70 ( 1993 )]. briefly , cells were fixed in 1 % buffered formaldehyde ( ph 7 . 4 ) for 15 min on ice , washed in phosphate - buffered saline ( pbs ) and stored at 4 ° c . in 70 % ethanol . subsequently , cells were resuspended in 50 μl of a solution containing : 5 unites of terminal deoxynucleotidyl transferase ( boehringer mannheim , indianapolis , ind . ), 2 . 5 mm cocl 2 , 0 . 2 m potassium cacodylate , 25 mm tris - hcl , 0 . 25 mg / ml bovine serum albumin , 0 . 5 nmoles biotin - 16 - dutp ( boehringer mannheim biochemicals , indianapolis , ind .). cells were incubated in this solution at 37 ° c . for 30 min , then rinsed in pbs and resuspended in 100 μl of staining solution , containing 2 . 5 μg / ml fluorescinated avidin , 4 × concentrated saline sodium citrate buffer , 0 . 1 % triton x - 100 , and 5 % ( w / v ) non - fat dry milk . cells were incubated in this solution for 30 min at room temperature in the dark . cells were then rinsed in pbs containing 0 . 1 % triton x - 100 and resuspended in 1 ml in pbs containing 5 μg / ml propidium iodide and 0 . 1 % rnase ( sigma ). green ( b - dutp ) and red ( dna ) fluorescence of individual cells were measured with an epics elite flow cytometer ( coulter , hialeah . fla ., usa ). in some examples below , methods were used to determine dna fragmentation . one method involves the demonstration of dna laddering on agarose gels . briefly , cells were lysed in te buffer containing 0 . 2 % triton x - 100 , ph 8 . fragmented dna was separated from intact chromatin by microfuging for 20 min , 14 , 000 rmp in 4 ° c . the resulting supernatant was treated with 1 mg / ml of proteinase k at 37 ° c . overnight , then extracted with phenol / chloroform / isoamyl alcohol ( 25 : 24 : 1 ) three times . dna was precipitated by addition of three volumes of absolute ethanol , in the presence of 0 . 3 m sodium acetate , ph 5 . 2 , and incubated overnight at − 20 ° c . and then pelleted by centrifugation at 14 , 000 rpm at 4 ° c . for 20 mil . the pellet was washed twice with 75 % ethanol and dissolved in 30 μl of te containing 10 μg / mil of rnase overnight at 37 ° c . dna samples were separated by electrophoresis on 1 . 8 % agarose gel in the presence of ethidium bromide . in some examples below , western blots were performed . for western blot analysis , 5 × 10 6 cells were washed and suspended in 100 μl of lysis buffer [ 1 % sodium dodecyl sulfate ( sds ), 1 mm sodium vanadate , 10 mm tris ( ph 7 . 6 )], and boiled for 5 min . after micro - centrifugation at 14 , 000 rpm , for 10 min , supernatants ( cell lysates ) were recovered . the protein concentration of the lysates was determined with bicinchoninic acid ( bca ) protein assay reagent ( pierce ). for cpp32 immunoblots , cell lysates ( 10 - 20 μg of protein per lane ) were separated on 15 % sds - polyacrylamide gels under reducing conditions , transferred to polyvinylidene difluoride ( pvdf ) membranes ( millipore ), and probed with mouse monoclonal anti - cpp32 ( clone # 19 , igg2a , from signal transduction labs , lexington , ky .) followed by sheep f ( ab ′) 2 fragment horseradish peroxidase - conjugated , anti - mouse ig ( amersham ). for parp immunoblots , cell lysates ( 10 μg of protein per lane ) were separated on 7 . 5 % sds - polyacrylamide gels , transferred to pvdf membrane , and probed with monoclonal mouse anti - human parp antibody c2 . 10 ( igg1 , enzyme systems products dublin , calif .). antibody binding was detected with an ecl detection system ( amersham ). in this example , the susceptibility of lymphocytes to cell death is examined . as noted above , it is believed that prevention of immune - mediated self injury requires prompt elimination of activated lymphocytes at the end of an immune response . in this example , the resistance of t cells of ra patients to anti - fas antibody - induced death is demonstrated . briefly , pha t cell lymphoblasts from 6 normal controls and 6 ra patients were established by stimulating peripheral blood mononuclear cells with 0 . 5 μg / ml pha for 3 days , followed by expansion in 20 u / ml of recombinant human il - 2 ( collaborative biomedical products , bedford , mass .). day - 10 t cell lymphoblasts were incubated with 125 ng / ml of the agonist anti - fas monoclonal antibody ch - 11 ( the antibody was immobilized and 1 × 10 5 cells per well were used ). in all experiments , control mouse monoclonal igm antibody ( tepc - 183 , from sigma ) was used in equivalent concentrations . cell death was determined at different time points , using a commercial mts kit ( promega , madison . wis .). microplate wells were read by elisa plate reader at 490 nm . fig2 a shows that activated lymphocytes of the t - cell lineage from normal individuals ( open squares ) die rapidly after exposure to the agonist anti - fas antibody ch - 11 . in contrast , t lymphocytes of ra patients ( open circles ) show complete resistance to killing up to 4 hours following ligation . some susceptibility , however , can be seen in these cells at the 24 hour time point . thus , at the critical early period , ra cells are resistant to killing by fas - ligation . fig2 b shows that activated lymphocytes of the b - cell lineage ( i . e . ebv transformed b cell lines ) from 4 normal individuals ( open squares ) also die rapidly . however , ebv transformed b cell lines from 5 ra individuals ( open circles ) show resistance to anti - fas antibody - induced death ( soluble anti - fas antibody was used and percent cell death determined as above ). fas - mediated cell death in - vivo is thought to be triggered , primarily , by cytotoxic t cells . lymphocytes expressing the vγ9 / vδ2 ( vgamma9 / vdelta2 ) t cell receptor have previously been found to display potent mhc - unrestricted cytolytic activity against a wide variety of targets and have been found in large numbers in the synovial fluid and peripheral blood of ra patients . the present inventors have found that ra and control b lymphoblastoid targets were equally capable of forming cell conjugates with vγ9 / vδ2 t - cells ( data not shown ). however , susceptibility to cytolysis is markedly different between the two groups when determined using standard 4 hour 51 cr release assays . fig2 c is a bar graph showing the susceptibility to cytolysis by vγ9 / vδ2 t cell clones determined in ebv transformed lines from 23 normal controls , 18 patients with ra , 6 patients with pauciarticular - onset juvenile arthritis (“ pja ”), and 3 patients with autoimmune thyroiditis . lymphoblastoid target lines from all 23 normal controls tested were efficiently killed by vγ9 / vδ2 clones , while none of the lines from 18 ra patients were susceptible . this resistance was disease - specific , since lines from 5 of 6 patients with another form of autoimmune arthritis ( pauciarticular - onset juvenile arthritis ), as well as lines from three patients with autoimmune thyroiditis , were all susceptible . the experiments in this example show that resistance of ra lymphocytes to killing is due to failed apoptosis . briefly , anti - fas antibody - mediated dna fragmentation by the tunel assay was performed in ebv transformed b cell lines from 6 normal controls ( fig3 a , open bars ) and 5 ra patients ( fig3 b , dashed bars ). cells were incubated with either the agonist anti - fas antibody , ch - 11 , or with isotype - matched control antibody , tepc - 183 before analysis of dna fragmentation . fas ligation resulted in dna fragmentation in control lymphocytes , but not in ra lymphocytes . anti - fas antibody - mediated dna fragmentation was also analyzed in ebv transformed b cell lines from 4 normal controls ( fig3 b , left ) and 4 ra patients ( fig3 b , right ) by agarose electrophoresis . again , cells were incubated with either the agonist anti - fas antibody , ch - 11 , or with isotype - matched control antibody , tepc - 183 before analysis of dna fragmentation . again , fas ligation resulted in dna fragmentation of control cells , but not ra lymphocytes . dna fragmentation by the jam assay was also performed in ebv transformed lines ( fig3 c ) from a normal control (□) and an ra patient (∘), subjected to γδ t cell - mediated killing . lack of dna fragmentation in ra target cells was also observed during vγ9 / vδ2 t - cell - mediated killing . while the present invention is not limited to any theory , it is believed that ra lymphocytes are not innately resistant to programmed cell death , as they display some susceptibility to fas - mediated cell death at the late time points , and more importantly , t - cells from both patients and controls are equally susceptible to apoptosis induced by il - 2 withdrawal ( data not shown ). resistance to anti - fas antibody - mediated apoptosis in ra lymphocytes is not attributable to reduced surface expression of the fas receptor , since equivalent levels of fas receptor expression could be found on lymphocytes of both the t and b cell lineage from normal individuals and ra patients . no differences in surface expression of cd4 , cd8 or cd45ro could be detected between normal and ra t cells . similarly , b cell lines from controls and ra patients expressed equivalent levels of cd30 and cd40 on their cell surface ( data not shown ). the above results suggest that an intracellular defect may be responsible for the observed resistance to apoptosis . the fas - mediated signaling cascade is initiated by oligomerization of the intracytoplasmic death domain and assembly of a death signaling complex . those events lead to activation of caspases such as yama / cpp32 ( caspase 3 ), that in turn cleave death substrates , including poly ( adp - ribose ) polymerase ( parp ) to a signature apoptotic form . thus , examination of downstream proteolytic events following fas ligation reports on the integrity of this pathway . in this example , it is demonstrated that activation of caspases is essential for fas - mediated apoptosis . briefly , cells were preincubated for 1 hr in the presence or absence of 40 μm of z - vad - fmk , and subsequently incubated with 100 ng / ml of the anti - fas antibody h - 11 . at different time points thereafter , cells were collected , lysed and a western blot analysis performed with the relevant antibodies . the results show the inhibitor z - vad - fmk blocks proteolytic processing of cpp32 ( fig4 a , upper panel ), cleavage of parp ( fig4 a , lower panel ), and subsequent cell death . the resistance of mcf7 targets transfected with crma cdna to killing by vγ9 / vδ2 t cell clones was also tested . the results show that caspases are also essential for apoptotic killing mediated by cytolytic vγ9 / vδ2 t cell clones , since mcf7 target cells expressing the cowpox virus crma are resistant to cytolysis ( fig4 b ). the fas pathway in ra lymphocytes was also examined for impaired activation of caspases . briefly , cells were incubated with 100 ng / ml of the anti - fas antibody , ch - 11 , over a time course and western blot analysis performed with the relevant antibodies . examination of the fas pathway in ra lymphocytes revealed impaired activation of caspases . in 4 of 4 normal lymphoblastoid b cell lines , but in none of 4 ra lines tested , proteolytic cleavage of cpp32 could be seen within 2 hours following fas ligation ( fig4 c ). similarly , cleavage of parp was detected in normal lines within 1 - 4 hours , but was undetectable in lines from ra patients ( fig4 d ). cleavage of cp32 and parp could be seen in ra lymphocytes at later time points ( data not shown ), suggesting that fas - mediated signals are being transduced , albeit inefficiently . to investigate the possibility that fas - mediated signals are being modulated by an exogenous inhibitor , the sphingomyelin pathway was studied , which has been previously shown to regulate fas - mediated apoptosis . no significant differences in either ceramide levels or sphingomyelinase activity could be found between control and ra lymphocytes ( data not shown ). however , when sphingosine and spp levels were quantitatively measured by the conversion of spp to tritiated n - acetyl - sphingosine - 1 - phosphate by acetylation with 3 h acetic anhydride , intracellular levels of these 2 ceramide metabolites were found to be significantly higher in ra lymphocytes . fig5 a shows the constitutive levels of sphingosine ( left ) and spp ( right ) in ebv transformed b cell lines from eight normal controls ( open bar ) and five ra patients ( hatched bars ). spp , a potent derivative of sphingosine , has been recently shown to activate a pertussis toxin - sensitive g protein and to inhibit fas - mediated cell death , therefore , the ability of spp to inhibit apoptosis in ra lymphocytes was investigated apoptosis induced by 8 hr stimulation with the anti - fas antibody ch - 11 ( 100 ng / ml ) was determined in ebv transformed target cells in the presence fig5 b , dashed bars ) or absence ( fig5 b , open bars ) of 2 . 5 μm dms in serum - free rpmi 1640 medium supplemented with insulin and transferrin . at the end of incubation , cells were washed and dna strand breaks were determined using the tunel assay . as can be seen , resistance of ra targets to apoptosis by anti - fas antibodies could be effectively reversed by prior incubation of target cells with the sphingosine kinase inhibitors , n , n - dimethylsphingosine ( dms ) or dl - threo - dihydrosphingosine ( dhs ). inhibition of fas - mediated death signaling by spp was also examined using γδ f cell clones . cytolysis of ebv transformed target cells by vγ9 / vδ2 t cells was determined by 4 hr 51 cr release assay ( fig5 c ) in the presence () or absence (∘) of 2 . 5 μm dms . at the end of incubation , targets were washed and susceptibility to killing by γδ t cells was assessed . a representative experiment with one ra target , out of five tested is shown in fig5 c . as can be seen , resistance of ra targets to apoptosis by γδ t cells could be effectively reversed by prior incubation of target cells with the sphingosine kinase inhibitors , n , n - dimethylsphingosine ( dms ) or dl - threo - dihydrosphingosine ( dhs ). additionally , pre - incubating ra targets with pertussis toxin reversed their resistance to fas - mediated and γδ t cell - mediated killing ( fig5 d and 5 e ). for assessing fas - mediated killing , ebv transformed b cell lines from eight normal controls ( fig5 d , left ) and six ra patients ( fig5 e right ) were preincubated with () or without (∘) pertussis toxin , 1μg / ml for 1 hr . at the end of incubation , target cells were washed and stimulated with 100 ng / ml of the anti - fas antibody ch - 11 over a time course . cell death was determined using the commercial mts kit ( promega , madison , wis .). for assessing γδ t cell - mediated killing ( fig5 e ), ebv transformed b cell targets were incubated for 1 hr with () or without (∘)) 1 μg / ml pertussis toxin as above . at the end of incubation , targets were washed and susceptibility to γδ t cell killing was determined using a 4 hr 51 cr - release assay . as noted above , it is not intended that the present invention be limited to any one inhibitor . in this example , resistance to fas - mediated cell killing is shown to be reversed by preincubation of target cells with a mek1 inhibitor . apoptosis of ra ebv transformed target cells was induced by 16 hr stimulation with anti - fas antibody ch - 11 ( 200 ng / ml ) in the presence ( fig6 black bars ) or absence ( fig6 open bars ) of 100 m of the mek1 inhibitor 2 -( 2 ′- amino3 ′- methoxyphenyl - oxanaphthalen - 4 - one ) ( pd098059 ). in this example , inhibitors are tested in an animal model . ra - like disease is inducible in certain strains of rats ( e . g .. lewis rats ) by immunization with mycobacterium tuberculosis (“ mt ”) in oil or cfa . see c . jacob et al ., “ heterogeneous effects of ifn in adjuvant arthritis ,” j . immunol . 142 : 1500 ( 1989 ). the disease is characterized by a self - limited , subacute polyarthritis and has been proposed as a model for human ra . rats are inoculated intradermally at the base of the tail with 0 . 1 ml cfa containing 10 mg / ml of heat killed mt in ifa ( difco laboratories , detroit , mich .). sphingosine derivatives ( methylsphingosine , dimethylsphingosine and trimethylsphingosine in separate rats ) are used as inhibitors of the sphingomyelin signal transduction pathway . the derivatives are prepared in a mixture containing a local anesthetic and injected intra - articularly . mt - reactive t cells from the joints are compared pre - and post - injection to assure that symptoms are reduced due to the administration of the inhibitor .