Suppression with anti-Ig of immunoglobulin secretion by pig lymphoblasts

Pig B lymphocytes are responsive to anti-immunoglobulin antibody, which triggers mitosis, and to lipopolysaccharide (LPS), which initiates both mitosis and differentiation of cells into lymphoblasts that synthesize and secrete immunoglobulin. In this study, the absence of Ig secretion after anti-Ig triggering of pig lymphocytes has been evaluated by observing the effects which anti-Ig has on cells already activated by LPS. Anti-Ig caused pronounced suppression of secretion of Ig by LPS-activated lymphoblasts in a dose-dependent fashion. The degree of suppression was not influenced by the time after LPS activation that anti-Ig was added to cells. IgG and F(ab')2 antibodies were equally suppressive; F(ab') antibody was less suppressive. Synthesis of Ig in anti-Ig-treated cells was not significantly altered. It is concluded that the surface Ig receptors of pig lymphocytes can have more than a single, initiating role in lymphocyte activation, and can also act as a pathway for regulating signals in differentiating B cells.