Activation and proliferation signals in mouse B cells. IV. Concanavalin A stimulates B cells to leave G0, but not to proliferate.

Concanavalin A (Con A), in solution, induces mouse T cells, but not B cells, to proliferate. However, lectin concentrations which were optimal for the T cell response induced purified B cells to depolarize, to enlarge, and to display increased levels of Ia antigens. Furthermore, culturing B lymphocytes with Con A for 24 hr caused the cells to synthesize DNA more rapidly in response to subsequent stimulation by lipopolysaccharide, or anti-immunoglobulin antibodies. This priming effect did not appear to require either T cells or accessory cells. It was therefore concluded that Con A activates resting B lymphocytes, i.e. stimulates them to enter the cell cycle, even though it does not induce B cells to divide.