[Mitogenic activity of Brucella fractions on cultured lymphocytes].

LPS from smooth B. melitensis extracted by the phenol-water method has no mitogenic activity for lymphocytes of men or mice uninfected by brucellosis, in amounts that are not toxic in vitro for these cells. Mitogenic activities of other B. melitensis fractions are evidenced only in amounts 100-fold greater than an effective dose of LPS from E. coli. We interpret these findings as reflecting a virgin immune status against brucella antigens.