<strong>B Cell Stim ulation:</strong> 5 x 10e5 SD Rat splenocytes were incubated with the indicated concentrations of purified Mouse F(ab')2 Anti-Rat IgM, clone M2A1, for 48 hours. B cell proliferation was determined by 3H-thymidineincorporation assay. Amount Used: < / = 10 μg/mL