Fetal calf serum and 2-mercaptoethanol induce anti-trinitrophenyl antibody production: II. Preferential stimulation of B cells in culture.

Fetal calf serum (FCS) and 2-mercaptoethanol (2-ME) are commonly used in culture media because they enhance lymphocyte responsiveness. We had previously reported that FCS and 2-ME generate high antitrinitrophenyl (TNP) antibody plaque-forming cell responses in unprimed murine spleen cells without added antigen. This was due in part to a component in FCS, which was antigenically cross-reactive with TNP. In the present report, we studied the mitogenic activity of FCS and 2-ME, which also contributed to the high anti-TNP response. Such mitogenic activity could not be replaced by B- or T-cell mitogens. Both FCS and 2-ME were required for the mitogenic activity, which was directed primarily at B cells. Purified T cells and spleen cells from B-cell-depleted mice were unresponsive to FCS and 2-ME stimulation. The mitogenic activity was not due to lipopolysaccharide (LPS) contamination of FCS, since cells of the LPS-unresponsive mouse strain, C3H/HeJ, were stimulated by FCS and 2-ME.