The effect of growth hormone and insulin upon MLC responses and the generation of cytotoxic lymphocytes.

The ability of growth hormone (GH) and insulin to influence positively T lymphocytes responding to an alloantigen stimulus in vitro was analyzed through the use of a serum substitute system. The presence of insulin but not GH, enables the generation of a successful mixed lymphocyte culture (MLC) blastogenic response. However, the presence of GH during a 5-day MLC allowed for the generation of cytotoxic T lymphocytes (CTL). It was further demonstrated that GH needed to be present during the first 2 days of the culture system, presumably before the entry of the precursor CTL into cell division. The results are discussed in terms of the induction, by the GH, of ornithine decarboxylase activity and how this might relate to the successful generation of CTL activity.