conflict of interest : jjf is a consultant for nkt therapeutics and receives research funding from nkt therapeutics and astellas .
red cell transfusions are frequently used to treat severe anemia and to reduce the effects of sickle cells . unlike many patient populations , patients with scd have a much higher risk of adverse events from transfusion therapy , due in part to known antigen incompatibility between blood donors , who are mostly of european descent , and the blood recipients , who are of african descent .
alloantibody formation in this population can be life - threatening , because delayed hemolytic transfusion reactions ( dhtr ) may sometimes initiate a hyperhemolytic process whereby there is not only hemolysis of transfused allogeneic cells but also the patient s own autologous cells . 
 
there are also descriptions of hyperhemolysis associated with autoantibodies , as well as cases with no antibodies . regardless of whether an antibody is present or
not , the end result of these hyperhemolytic events is a profoundly low hemoglobin , even lower than pre - transfusion levels . despite profoundly low hemoglobin values
in addition to avoidance of transfusions , therapies are often directed at suppressing the immune system ( i.e. corticosteroids and ivig ) .
we identified an associated autoantibody that caused robust hemolysis and severe anemia , which was temporally associated with end - organ dysfunction and death .
what makes this case unique is that the predominant organ affected was not the brain or the lung , but the bone marrow .
bone marrow ischemia , the cause of vaso - occlusive pain , is common in scd ; however , extensive bone marrow necrosis is rare .
this case underscores the risks associated with transfusion in scd , especially in a heavily alloimmunized patient .
a 61 year - old female with hemoglobin sc disease on hydroxurea , a history of multiple red cell alloantibodies ( anti - e , -jk , -k , -n , -s , -cw , and  js ) and previous delayed hemolytic transfusion reactions ( last recorded red cell transfusion was 3 years before the current admission ) , a chronic pain syndrome , and g6pd deficiency , presented to the hospital due to a vaso - occlusive pain crisis . on admission ,
her pain was reported to be located in her chest and back , which was similar to her previously reported chronic pain crises .
her presenting laboratory tests were notable for a hemoglobin of 5.3 g / dl ( baseline of 8 - 9 g / dl ) , a platelet count of 120,000 cells / ul ( baseline of 140,000 cells / ul ) , and normal renal function ( baseline : 0.8 mg / dl ) .
the blood bank work - up , however , was significant for a newly positive direct antiglobulin test ( dat ) ( polyspecific : 1 + , anti - igg : weak , anti - c3 : negative , eluate : negative ) , and a new anti - mcc , which was considered not clinically significant and has not been reported to cause hemolysis ( table 1 ) .
she was started on a hydromorphone patient - controlled analgesia pump for pain management , and she was transfused two units of least incompatible ( incompatibility was from the new anti - mcc ) , abo compatible ( patient : b+ ) , leukocyte - reduced , sickle negative , and antigen - matched ( e- , jk(b- ) , k- , s,- by serology , and c- and js(a- ) by genotype ) red blood cells ( rbc ) , with no complications and an appropriate increase in hemoglobin to 7.4 g / dl . on her second day of admission ( hd 2 ) , her platelet count unexpectedly decreased to 61,000 cells / ul , and her count continued to decline through her hospitalization .
as her reticulocyte count was also inappropriately low at the time ( 0.012 e6/l ) , her worsening thrombocytopenia was felt most likely to be due to myelosuppression from hydroxyurea .
consequently , in addition to halting the hydroxyurea , she also received epoetin alfa ( 40,000 units sq ) for marrow stimulation . despite holding hydroxyurea and the dose of epoetin
, she required an additional 4 units of phenotype - matched rbcs ( 1 unit  hd 5 , 1 unit  hd 8 , 2 units  hd 12 ) during the hospitalization to maintain her hemoglobin level .
although immune hemolysis was suspected at the time , no additional antibodies were identified ( table 1 ) .
after her pain improved , she was discharged on hospital day 12 with a hemoglobin of 9.1 g / dl and a platelet count of 20,000 cells / ul ( a discharge lactate dehydrogenase ( ldh ) and total bilirubin were not performed ) . at her first outpatient follow - up , 6 days after discharge ( about 7 days from her last red cell transfusion ) , she reported new symptoms of fatigue , shortness of breath , and worsening pain .
her hemoglobin at this visit was 2.7 g / dl , and platelet count was 20,000 cells / ul . of note ,
her reticulocyte percent was below the level of detection ( < 0.4% ) despite an erythropoietin level that was elevated at 132 miu / ml ( reference : 3.7 - 31.5 miu / ml ) .
her laboratory results were consistent with intravascular red cell hemolysis : ldh was > 2500 u / l ( ref : 100 - 190 u / l , her baseline was 342
u / l ) , haptoglobin was 18 mg / dl ( ref : 30 - 200 mg / dl ) , and her total bilirubin was 5.0 mg / dl ( ref : 0.2 - 1.0 mg / dl ) with hemoglobinuria detected on urine screen .
there was no evidence of disseminated intravascular coagulation , and no schistocytes were observed on her peripheral smear .
her dat was now strongly positive , with 3 + polyspecific ahg , 1 + igg , 2 + c3 reactivity , and an eluate that was positive with all cells . of interest , the patient also had a new cold autoantibody with broad specificity and shown to react at body temperature ( 30 and 37 c ) as defined by thermal amplitude studies , suggesting a clinically - significant mixed ( igg / igm ) autoantibody .
she was hospitalized again , and was given 2 units of compatible rbcs ( with an appropriate immediate post - transfusion response , post - transfusion hemoglobin 5.2 g / dl ) , epoetin alpha ( 40,000 units sq ) , and prednisone ( 1 mg / kg daily ) for a presumed mixed - type ( igg / igm ) hyperhemolysis syndrome ( figure 1 ) .
. on hd 3 of readmission , she was started on intravenous immunoglobulin ( ivig ) at 500 mg / kg , received another dose of epoetin alpha ( 40,000 units ) , and 2 units of rbcs .
she further developed evidence of marrow failure ( white count , 2,200 cells / ul ) on hd 4 prompting a bone marrow biopsy , which revealed diffuse and widespread bone marrow necrosis ( figure 2 ) .
due to worsening of her thrombocytopenia , romiplostim ( 2 mcg / kg ) and 2 platelet transfusions were attempted without any meaningful effect on hd 10 ( figure 1 ) .
she developed multisystem organ failure and continued to decline cognitively during the hospitalization , and was transitioned to comfort care .
we present a unique case of transfusion - induced hyperhemolysis in an adult with scd . in this
heavily alloimmunized , recently - transfused patient , an autoantibody that triggered hyperhemolysis was likely the key insult that ultimately led to her death .
upon presentation with vaso - occlusive pain , the dat was only weakly positive , but after the patient received red cell transfusions , there was evidence that the autoantibody strengthened .
later in the clinical course , laboratory testing clearly demonstrated complement - coated red cells , as well as a new clinically - significant mixed warm and cold autoantibody .
the strengthening of the autoantibody was associated with worsening hemolysis and a clinical picture consistent with acute hyperhemolysis : a recent transfusion ( about 7 days before the hemoglobin nadir ) , a new red cell antibody , reticulocytopenia , and a severe anemia ( well below pre - transfusion levels ) .
unfortunately , in this case , the severe anemia and resultant ischemia from red cell hemolysis likely fatally exacerbated extensive , clinically - significant bone marrow necrosis ; a process that likely began during her first hospitalization as reflected by her progressively strengthening dat and worsening thrombocytopenia during that time period .
hyperhemolysis syndrome is a well - reported and life - threatening complication of red cell transfusions for patients with scd .
clinically , the typical presentation of acute hyperhemolysis is severe anemia , developing about 7 days after a previous transfusion , with a hemoglobin that is lower than pre - transfusional levels .
other common findings include reticulocytopenia , pain , fever , and signs of hemolysis , including jaundice , increased ldh , hyperbilirubinemia , and hemoglobinuria . while hyperhemolysis has no definitive diagnostic test , there is sometimes evidence of a new allo- or autoantibody .
one potential reason for the autologous rbc destruction in these patients is the formation of a nonspecific antibody that binds complement and destroys both donor and recipient red cells , known as bystander hemolysis . as in our patient ,
previous studies have shown a strong association between the formation of nonspecific autoantibodies and the history of previous transfusions .
another explanation for excess patient rbc destruction is the hyperactive phagocytic activity of macrophages . of note ,
sickled rbcs expose some antigens ( e.g. phosphatidylserine ) on their outer surface , which some the - orize can allow recognition by activated macrophages without antibody interactions .
others consider the interaction between vcam-1 and 41 on sickled red cells , and cd11c and icam-4 on transfused donor red cells , to be critical for antibody - independent phagocytosis by activated macrophages in patients with scd .
lastly , suppression of erythropoiesis has also been proposed as a cause or modulator of the disease .
the severity of this patient s anemia ( hemoglobin of 2.7 g / dl ) , was notable .
first , as mentioned above , this patient had an ongoing reticulocytopenia that prevented an appropriate response in the face of hemolysis .
the reticulocytopenia may have developed from bone marrow necrosis and , potentially , the immune - mediated hemolysis of red cell precursors as well .
second , the cold autoantibody active at 30c likely contributed to a more severe hemolysis .
a recent study suggests that mixed - type immune hemolytic anemias may be more severe than other forms of immune hemolysis , with 63% of mixed hemolysis patients presenting with a hemoglobin < 6 g / dl in comparison to 29% of patients with typical warm autoimmune hemolytic anemia , and 9% of patients with cold agglutinin disease , respectively .
moreover , hyperhemolysis in a patient with scd and a clinically significant cold autoantibody , anti - ih , has contributed in at least one reported fatal outcome from hyperhemolysis .
our case , however , is the first where the hemolysis from a mixed - type auto agglutinin led to profound bone marrow failure .
extensive bone marrow necrosis that affects hematopoiesis is a rare , but established , complication in patients with scd .
greater than 90% of cases of bone marrow necrosis occur in the context of other diseases such as cancer , most often hematological malignancy , infection or autoimmune conditions .
bone marrow necrosis in scd encompasses a broad spectrum of severity , from a localized process to one that is widespread . given that one of the most common sites for vaso - occlusion is in the bone marrow , aspirates often reveal patches of necrotic marrow , although rarely extensive enough to impact hematopoiesis , as was seen in our case .
common symptoms of bone marrow necrosis include back pain , fever , cytopenias and a leukoerythroblastic picture ( immature white blood cells and nucleated red cells in peripheral blood ) .
large autopsy studies suggest that the prevalence of diffuse bone marrow necrosis can range from 0.2 - 15 percent of susceptible patients . as of 2016 ,
about 60 cases of severe bone marrow necrosis in patients with scd has been reported in the literature . to our knowledge
, none of these were reported to be precipitated by a previous red cell transfusion . of those reported cases ,
64% had a fatal outcome and only 12 patients ( 21% ) documented complete recovery , all after receiving red blood cell exchanges .
death from extensive marrow necrosis is secondary to the dissemination of fat emboli , acute multi - organ system failure , and acute chest syndrome episodes .
there is no standard approach to the treatment of hyperhemolysis or extensive bone marrow necrosis . in the case of hyperhemolysis ,
transfusion of red cells is usually avoided , because it may precipitate increased bystander hemolysis and macrophage activation .
our patient did receive red cell transfusions , especially when the clinical picture was unclear during her first admission .
otherwise , our patient was treated with steroids and ivig to decrease antibody production and reduce the clearance of antibody - laden red cells , as has been reported to be beneficial in the literature .
growth factors are also a mainstay , especially epoetin alpha , since reticulocytopenia is often a presenting feature .
erythropoietin can correct anemia by stimulating red cell precursors and also mitigate the destruction of young red cells .
additionally , rituximab ( anti - cd20 ) has been used in some cases with success . while we had some evidence that the patient s immune hemolysis was improving ( her direct antiglobulin test was showing weakening of her igg and c3 values during her second hospitalization ) , these therapies likely had no impact on her final outcome as none of these therapies will aid in bone marrow recovery .
simple or exchange red cell transfusions may be beneficial for bone marrow necrosis to improve oxygenation and blood flow to the ischemic marrow ; unfortunately , aggressive transfusion therapy was not an option for our patient .
this case demonstrates the unique risks of red cell transfusions in a patient with scd .
severe anemia associated with hyperhemolysis was likely what caused the bone marrow necrosis that ultimately led to this patient s death .
the bone marrow biopsy , which ultimately clarified her pancytopenia , should be seriously considered in patients with scd when severe anemia , reticulocytopenia , and thrombocytopenia are observed together . in conclusion ,
an awareness of the potential for serious complications , such as hyperhemolysis , is necessary when determining the need for transfusion in a patient with scd .
 in patients with sickle cell disease , hyperhemolysis is a rare but life - threatening complication of transfusion . in this case report , we describe a 61 year - old woman with hemoglobin sickle cell ( sc ) disease and history of alloimmunization who developed hyperhemolysis associated with a transfusion . 
 she was found to have a warm and a clinically - significant cold autoantibody . 
 severe anemia ( hb 2.7 g / dl ) with reticulocytopenia and thrombocytopenia prompted a bone marrow biopsy , which demonstrated extensive bone marrow necrosis . despite treatment , the bone marrow failure did not improve and the patient died on hospital day 38 . 
 this case illustrates the potential risks of transfusion in a patient with sickle cell disease , especially one with previous hemolytic reactions . while uncommon 
 , hyperhemolysis can cause death , in this case by extensive bone marrow necrosis . in patients with sickle cell disease , judicious use of red cell transfusions with phenotypically - matched units can diminish , but never completely abrogate , the risks associated with transfusion . 
Competing interest statement
Introduction
Case Report
Discussion and Conclusions