Platelet counts during SM. A: Platelet counts 7 days after infection. Wild-type mice (+/+) are significantly thrombocytopenic, compared to noninfected mice (n = 8, P < 0.01), whereas thrombocytopenia is significantly (P < 0.05) attenuated in infected CD40−/− and CD40L−/−, compared to +/+ mice. B: Values are the mean (+SD, n = 7) of the platelet counts 7 days after infection. Infected +/+ mice were treated on the 6th day after infection with nIgG or anti-CD40L mAb.