title: Fc receptor-mediated phagocytosis makes a significant contribution to clearance of influenza virus infections.
abstract: Fc receptors for IgG expressed on macrophages and NK cells are important mediators of opsonophagocytosis and Ab-dependent cell-mediated cytotoxicity. Phagocyte-mediated opsonophagocytosis is pivotal for protection against bacteria, but its importance in recovery from infection with intracellular pathogens is unclear. We have now investigated the role of opsonophagocytosis in protection against lethal influenza virus infection by using FcR gamma(-/-) mice. Absence of the FcR gamma-chain did not affect the expression of IFN-gamma and IL-10 in the lungs and spleens after intranasal immunization with an influenza subunit vaccine. Titers of serum and respiratory Abs of the IgM, IgG1, IgG2a, and IgA isotypes in FcR gamma(-/-) mice were similar to levels seen in FcR gamma(+/+) mice. Nevertheless, FcR gamma(-/-) mice were highly susceptible to influenza infection, even in the presence of anti-influenza Abs from immune FcR gamma(+/+) mice. NK cells were not necessary for the observed Ab-mediated viral clearance, but macrophages were found to be capable of actively ingesting opsonized virus particles. We conclude that Fc receptor-mediated phagocytosis plays a pivotal role in clearance of respiratory virus infections.
authors.affiliation: Center for Immunology and Microbial Disease, Albany Medical College, Albany, NY 12208, USA.
authors.forename: V C
authors.initials: VC
authors.lastname: Huber
authors.forename: J M
authors.initials: JM
authors.lastname: Lynch
authors.forename: D J
authors.initials: DJ
authors.lastname: Bucher
authors.forename: J
authors.initials: J
authors.lastname: Le
authors.forename: D W
authors.initials: DW
authors.lastname: Metzger
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D017252:CD3 Complex; D002460:Cell Line; D016207:Cytokines / Q000096:biosynthesis; D020022:Genetic Predisposition to Disease; D006801:Humans; D007106:Immune Sera / Q000008:administration & dosage; D007116:Immunization, Passive; D007132:Immunoglobulin Isotypes / Q000096:biosynthesis; D009980:Influenza A virus / Q000276:immunology; D007251:Influenza, Human / Q000235:genetics / Q000276:immunology* / Q000517:prevention & control* / Q000821:virology; D007274:Injections, Intraperitoneal; D008168:Lung / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D018345:Mice, Knockout; D008822:Mice, Transgenic; D010587:Phagocytosis / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D011961:Receptors, Fc / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D013154:Spleen / Q000276:immunology / Q000378:metabolism
chemical_list: D000914:Antibodies, Viral; D017252:CD3 Complex; C115335:CD3E protein, human; D016207:Cytokines; D007106:Immune Sera; D007132:Immunoglobulin Isotypes; D011948:Receptors, Antigen, T-Cell; D011961:Receptors, Fc