HUMAN T-CELL CLONES IN LONG-TERM CULTURE AS A MODEL OF IMMUNOSENESCENCE

We have consistently observed that like other normal somatic tissue ce lls, human T lymphocytes manifest a finite proliferative capacity in c ulture in vitro. When measured in population doublings (PD), this aver ages about 35 PD for T-cell clones (TCC) derived from mature periphera l T cells of young adults and about 20 PD more for TCC derived from T- cell precursors in their bone marrow. We believe that alterations in s urface marker phenotypes and corresponding functional changes observed in these human TCC as they progress through their finite lifespans in vitro can provide valuable information on processes of T-cell immunos enescence in vivo. They may also provide a model system for studying w ays of modulating the ageing process to delay or prevent immunosenesce nce in the elderly and the chronically infected or possibly to acceler ate immunosenescence in organ transplantation.