irradiating the mixture of {HEAD ~ leukocytes} in {TAIL ~ the presence} of a psoralen at a temperature between about 20° C. and about 28° C.; followed by 
irradiating the mixture of { HEAD ~ leukocytes } in { TAIL ~ the presence } of a psoralen at a temperature between about 20 ° C. and about 28 ° C. ; followed by
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH