Studies on the effect of a thymic humoral factor on differentiation of thymus‐derived lymphocytes

Publisher Website
Google Scholar
Abstract
The effect of a thymic humoral factor (THF) on differentiation of thymus‐derived (T) lymphocytes was studied in various graft‐versus‐host models. It was demonstrated that THF, which is known to be capable of restoring immunocompetence of cells from neonatally thymectomized mice, does not act on lymphoid populations devoid of T cells. Immunologically defective lymphoid cells such as spleen cells obtained from mice treated with anti‐lymphocyte serum could be activated by THF by in vivo or in vitro interaction. These experiments indicate that the target cell acted upon by THF is a T cell with a low level of immunocompetence. It is suggested that THF acts on young T cells and transforms them into mature T cells active in cell‐mediated immune reactions, presumably without substantial multiplication.