MD-1–deficient B cells are impaired in LPS-induced B-cell proliferation.

Purified spleen B cells prepared from wild-type (■) or MD-1–deficient mice (▪) were stimulated for 3 days with anti-CD40 (10 μg/mL); anti-RP105 (2 μg/mL); lipid A (0.01, 0.1, and 1.0 μg/mL); LPS from S minnesota Re595 or E coli 055: B5 (0.01, 0.1, and 1.0 μg/mL). [³H]-TdR uptake was counted as described in “Materials and methods.” Results were shown as mean values of count per minute (cpm) from triplicate wells with standard errors. When compared with wild-type B cells, MD-1–deficient B cells showed significant hyporesponsiveness to LPS as revealed by the following P values: lipid A 0.01 μg/mL,P < .001; lipid A 0.1 μg/mL, P < .002; lipid A 1.0 μg/mL, P < .003; Re595 0.01 μg/mL,P < .011; Re595 0.1 μg/mL, P < .001; Re595 1.0 μg/mL, P < .0001; 055:B5 0.01 μg/mL,P < .11; 055:B5, 0.1 μg/mL, P < .002; 055:B5 1.0 μg/mL, P < .001.