Additional dose of the antigen at the end of the log phase of developing IgM response to T-dependent antigen leads to a drastic increase in the counts of IgM and IgG antibody-producing cells in the spleens of experimental animals. The effect is dose-dependent and more pronounced after the first immunization with the antigen in the suboptimal dose. Elimination of proliferating antibody producers has an ambiguous effect on IgM and IgG antibody production in the spleen: it limits the increase in the count of IgM-producing cells, but does not abolish the stimulation of IgG response. It seems that the increase in the count of IgG producers is not linked with simultaneous active proliferation of IgG producing cell precursors.