Preferential decrease in thymus dependent lymphocytes during storage at 4 C in anticoagulant.

Human lymphocytes stored at 4 C either as leukocyte concentrates (LCs) in citrate-phosphate-dextrose (CPD) or as whole blood anticoagulated with CPD show a rapid and marked decrease in the relative and absolute numbers of thymus derived (T) lymphocytes. Determinations were made on cells recoverable on a Ficoll-Hypaque (F-H) gradient. In evacuated LCs, the relative percentage of T cells dropped to less than 10 per cent within 72 hours with a concomitant increase in the relative percentage of bone marrow derived (B) cells to 80 per cent or more. LCs opened to the air and subsequently stored at 4 C displayed an even more precipitous decline in the relative percentage of T cells, reaching a 10 per cent level within 72 hours. The relative percentage of T cells in CPD-anticoagulated whole blood samples stored at 4 C displayed similar decreases, reaching 20 per cent levels within 24 hours. The change in the relative percentage of T cells at the Ficoll-Hypaque interface was shown to reflect a decrease in the total numbers of T cells placed on the F-H gradient with time, since determinations of T and B cell numbers in NH4Cl-treated whole blood showed a 65 to 80 per cent decrease in the numbers of T cells within 24 hours in anticoagulated whole blood held at 4 C. Thus, it may be inferred that the T cell decrease is mediated via some interaction of anticoagulant, storage time, and some component(s) present in both LCs and whole blood.