IgM secretion and proliferation of MWCL-1 cells in response to cytokines. MWCL-1 cells were cultured with the indicated cytokines for 72 hours, at which time IgM secretion was quantified by enzyme-linked immunosorbent assay (A), and DNA synthesis measured by ³H-TdR incorporation (B). Bars represent the mean of triplicate experiments ± SD. *Value significantly higher than in the respective untreated control cells (P < .05).