Influence of autoclaved Brucella melitensis on the proliferation of human lymphocytes

Brucella melitensis is a facultative intracellular bacterium which binds spontaneously to human B-lymphocytes. In order to find out whether there exists a relation between bacterial adherence and lymphocyte reactivity, the proliferation response of normal adult peripheral blood lymphocytes to autoclaved B. melitensis has been studied. Our results indicate that autoclaved B. melitensis induce only a slight increase in proliferation. This low lymphocyte response is due to proliferating B-cells. In high doses B. melitensis inhibited the response of lymphocytes to Concanavalin A and phytohaemagglutinin. This effect is probably due to the presence of lectin binding saccharides on the bacterial surface competing with the T-cells for the mitogens.