A mitogen for human B cells: anti-Ig coupled to polyacrylamide beads activates blood mononuclear cells independently of T cells.

The F(ab')2 fragment of rabbit anti-human F(ab')2 antibodies covalently linked to polyacrylamide beads (anti-Ig beads) acts as a polyclonal mitogen for human B cells in whole peripheral blood mononuclear cells (PBM) or tonsil cells. Activation, measured by the rate of DNA synthesis, is the result of an interaction between the anti-Ig beads and membrane immunoglobulin found on B cells. Excess soluble human F(ab')2 blocks activation with anti-Ig beads. Immunospecifically purified antibodies against IgM or IgD bound to beads activate lymphocytes. Also soluble anti-IgM or anti-IgD can block activation with insolubilized anti-IgM or anti-IgD, respectively, by modulating membrane immunoglobulin. Irrelevant rabbit antihapten antibodies bound to beads failed to activate PBM or tonsil cells. Anti-Ig beads act independently of T cells. The anti-Ig beads lead to activation of B cells without further maturation to polyclonal immunoglobulin secretion.