The stimulation of immunoglobulin production in murine spleen cells by the pokeweed mitogens.

We have shown that of the five mitogens purified from the salt extracts of pokeweed, only Pa-1, the B cell mitogen, has the ability to stimulate immunoglobulin production in murine B cells in the absence of classical T cells. Furthermore, the T cell mitogens (Pa-2-Pa-5) not only are unable to stimulate DNA or immunoglobulin synthesis by B cells in the absence of T cells, but cannot stimulate immunoglobulin production by B cells even in the presence of T cells. This suggests that Pa-2-Pa-5 do not stimulate adequate helper function in T cells or that if such a helper function is stimulated, an additional stimulatory factor is required for immunoglobulin production, which is not provided for by Pa-2-Pa-5.