Immunocompetence of T lymphocytes during whole-blood storage

In WB stored for 28 days at 4 degrees C the pattern of peripheral T-cell CD25 (IL-2R) expression after polyclonal in vitro stimulation was examined. Flow cytrometic analysis was performed with lymphocytes after 72 h in culture with and without ConA using antibody against CD3 and CD25. In culture supernatants IL-2 was determined. T-cells bearing the CD25 marker decreased with storage time, the mean fluorescence (i.e., number of IL-2R molecules per cell) remained rather stable. IL-2 concentrations peaked with stimulated cells which have been stored for 6 days. The low detectable levels of IL-2 in cultures of T-cells which have not been stored may reflect a much more efficient interplay of IL-2/IL-2R. Thus, even after longer periods of blood storage there are sufficient numbers of T-cells which can be stimulated to excite preprogrammed effector functions, i.e. also a GVHD.