Cutting Edge: Role of B Lymphocytes in Protective Immunity Against Salmonella typhimurium Infection

Abstract

Infection of mice with Salmonella typhimurium gives rise to a disease similar to human typhoid fever caused by S. typhi. Since S. typhimurium is a facultative intracellular bacterium, the requirement of B cells in the immune response against S. typhimurium is a longstanding matter of debate. By infecting mice on a susceptible background and deficient in B cells (Igμ−/− mice) with different strains of S. typhimurium, we could for the first time formally clarify the role of B cells in the response against S. typhimurium. Compared with Igμ+/+ mice, LD50 values in Igμ−/− mice were reduced during primary, and particularly secondary, oral infection with virulent S. typhimurium. After systemic infection, Igμ−/− mice cleared attenuated aroA− S. typhimurium, but vaccine-induced protection against systemic infection with virulent S. typhimurium involved both B cell-dependent and -independent effector mechanisms. Thus, B cell-mediated immunity plays a distinct role in control of S. typhimurium in susceptible mice.