We also found that CD40 KO and CD40L KO mice, both of which are highly susceptible to Pneumocystis infection, had measurable levels of MAIT cells similar to those found in C57BL/6 mice (data not shown), suggesting that MAIT cells are insufficient to control infection in the setting of a defective adaptive immune response. The gene discussed is CD40; the disease is Pneumocystis infectious disease.