Enhanced clonability of human T lymphocytes caused by their culturing in vitro

Human lymphocytes precultured for 24--48 hr form more T-lymphoid colonies (LT-CFU) in agar than do fresh cells. It appears that during the preculture period lymphocytes proceed from G0 to the next S phase, a process that is dependent upon active cellular metabolism. Thus, lymphoproliferation as assayed by LT-CFU growth appears to be controlled by short-lived suppressor cells (SLSC) which may be similar to those described for blastogenesis evaluated by thymidine incorporation assay. The activity of SLSC operating in LT-CFU system may be controlled by prostaglandins.