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