Anti-Ig antibody inhibits the phorbol ester-induced stimulation of peritoneal B cells.

Peritoneal B cells are stimulated to enter S phase by phorbol esters acting alone, in the absence of a co-mitogen. Anti-Ig antibody inhibited the stimulation of peritoneal B cells induced by phorbol esters and this inhibition was apparent throughout the time course of PMA-induced stimulation. Assessment of inhibition after depletion of Ly-1+ B cells suggested that PMA-induced stimulation of both Ly-1+ and Ly-1- B cells was affected by anti-Ig. Inhibition produced by anti-Ig was substantially reduced after even a brief delay in the addition of antibody to PMA-stimulated B cells. Anti-Ig antibody may counteract early events triggered by PMA within minutes of peritoneal B cell stimulation.