Promotion of murine B cell differentiation by 2-mercaptoethanol in contrast to glutathione.

The role of thiol compounds in B cell proliferation and differentiation was investigated with a stable, homogeneous population of an antigen-specific plasmablastoma, 2C3. This cell line expresses both membrane and secreted forms of immunoglobulin and is arrested at an intermediate stage of B cell development. Attempts to induce its differentiation into plasma cells using antigen, anti-idiotypic antibodies, or mitogens were unsuccessful. However, cultivation of 2C3 in the presence of 2-mercaptoethanol (5 x 10(-5) M) changed its doubling time from 19.8 to 34.9 h. There was also a significant rise in intracellular glutathione and in immunoglobulin production, but little change in non-Ig protein secretion. In contrast, exposure of 2C3 to exogenous glutathione (5 x 10(-3) M) reduced the doubling time to 11.0 h, with marked increases in proliferation. Moreover, there was no significant rise in either intracellular glutathione or immunoglobulin secretion. Distinct morphological differences were also apparent at the ultrastructural level. Thus, there is a dichotomy in the action of the two thiols. Although the effects of 2-mercaptoethanol could not be reversed, the two thiols together abrogated each other's effects, implying that their actions may be mediated through a common regulatory pathway.