Human colostrum contains an activity that inhibits the production of IL-2.

The effect of human colostrum on T cell immune function was investigated. Colostrum inhibited the proliferation of human T cells activated by allogeneic, concanavalin A (Con A) or phytohaemagglutinin (PHA) stimulation. Colostrum also inhibited the production of IL-2 by Con A-activated human peripheral blood T cells and by Con A-activated Jurkat cells, a human T lymphoma line. Similarly, human colostrum inhibited the production of IL-2 by EL4 cells, a murine thymoma line, when stimulated with phorbol myristate acetate. The inhibitory activity was not cytotoxic and could not be neutralized by antibody to transforming human growth factor beta.