Proliferative responsiveness of spleen cells to stimulation with HA and anti-CD44 antibodies. Spleen cells (6 × 10⁵) from normal C57BL/6 mice were cultured in the absence (control) or presence of anti-CD3 (1:200 dilution), LPS (50 μg/mL), anti-IgM (20 μg/mL), HA (0.5 mg/mL), or anti-CD44 MoAbs (KM201, 1:10 final dilution). After 42 hours of culture, the cells were pulsed with ³H-thymidine and 6 hours later, the cells were harvested and ³H-thymidine incorporation in the DNA was measured. The vertical bars represent mean counts per minute (CPM) of triplicate cultures ± standard error (SE)