Inhibition by colostrum of the responses of peripheral blood mononuclear cells to mitogens.

This study investigated the inhibition by colostrum of the uptake of tritiated thymidine by both autologous and heterologous peripheral blood mononuclear cells (PBMC) stimulated with the mitogens phytohaemagglutinin (PHA), pokeweed mitogen (PWM) or Concanavalin A (Con A). This inhibition was not the result of an alteration in the dose response or kinetics of mitogenesis by the colostrum. The inhibitory factor in the colostrum was neither dialysable nor lymphocytotoxic. Lymphocytes which were briefly pre-treated with colostrum, then washed and cultured, also incorporated much less labelled thymidine than control cells. The inhibitory factor was not adsorbed from colostrum by mononuclear cells. We conclude that colostrum contains a cytostatic factor which inhibits mitogenesis in PBMC.