The effect of anti-immunoglobulin antibodies on the in vitro proliferation and differentiation of normal and neoplastic murineB cells.

In these studies, we have compared the effects of anti-mu and anti-delta antibodies on normal and neoplastic murine B cells. Spleen cells from normal BALB/c mice or from mice carrying the BCL1 tumor were treated with F(ab')2 fragments of affinity purified anti-mu or anti-delta antibodies and the effec of the antibodies on cell proliferation was assessed. F(ab)'2 fragments of both antibodies induced proliferation of normal adult B cells but inhibited (anti-mu) or had no effect (anti-delta) on proliferation of BCL1 cells. In addition, both antibodies further enhanced the LPS-induced proliferative response of cells from adult mice. In contrast, the LPS responses of neonatal cells and BCL1 cells were inhibited by F(ab')2 anti-mu antibodies. These data indicate that interaction of antibody with surface IgD as well as surface IgM can activate adult B cells. In addition, the results provide further evidence that BCL1 cells are neoplastic analogs of immature B cells since the tumor cells, like neonatal cells, are not activated after treatment with anti-Ig antibodies.