Enhancement of immunoglobulin secretion by the lymphokine-like activity of a Mycoplasma arginini strain.

B lymphocytes, preactivated by lipopolysaccharide (LPS), could be triggered to growth by a strain of Mycoplasma arginini, while the level of immunoglobulin (Ig) secretion, quantitated as the number of plaque-forming cells (PFC), was low. The PFC response could be increased by the addition of conditioned media (CM) from lectin-activated spleen cells or T cell tumour EL-4 to the culture of preactivated B cells. CM did not by itself induce a significant amount of PFC in the cultures of LPS-preactivated B cells. The maturation enhancing activity was distinct from IL-2 and B cell growth factor as judged by gel exclusion chromatography.