The essential role of complement in antibody-mediated resistance to Salmonella.

Omar Rossi, Chris Coward, Yun Shan Goh, Jill WC Claassens, Calman A MacLennan, Sjef J Verbeek, Pietro Mastroeni

OAI: oai:www.repository.cam.ac.uk:1810/285053 • DOI: 10.17863/CAM.32423

Vaccines can serve as essential tools to prevent bacterial diseases via the induction of long-lasting IgG responses. The efficacy of such vaccines depends on the effector mechanisms triggered by IgG. The complement system and Fc-gamma receptors (FcγRs) can potentially play a crucial role in IgG-mediated immunity against bacterial diseases. However, their relative importance in vivo is unclear, and has been the object of controversy and debate. In this brief study, we have used gene-targeted mice lacking either FcγRI, II, II and IV or the C3 complement component as well as a novel mouse strain lacking both C3 and FcγRs to conclusively show the essential role of complement in antibody-mediated host resistance to Salmonella enterica systemic infection. By comparing the effect of IgG2a antibodies against Salmonella O-antigen in gene-targeted mice, we demonstrate that the complement system is essential for the IgG-mediated reduction of bacterial numbers in the tissues.

salmonella In vivo C3 FcγR complement Infection Animals Bacterial Load Complement Activation Complement C3 Humans Immunity Humoral Immunoglobulin G Mice Mice Inbred C57BL Mice Knockout O Antigens Receptors IgG Salmonella Infections Salmonella Vaccines Salmonella enterica