Effect of the progesterone-inducible proteins human lactoferrin and chicken avidin on lymphocyte proliferation

Lactoferrin and avidin are progesterone-inducible glycoproteins in the human and chicken reproductive tracts, respectively. The effect of these proteins on lymphocyte proliferation was studied. The results showed that both proteins suppressed Concanavalin A (Con A)-induced responses so that a 10(3)-fold higher concentration of Con A was required for an optimal response. In contrast, avidin and lactoferrin had no effect on lymphocyte proliferation induced by other mitogens, tuberculin PPD or allogeneic cells. The effect of lactoferrin and avidin on lymphocyte proliferation seem to be caused by their binding to Con A. The significance of these findings is discussed.