title: Fc receptor-mediated antibody regulation of T cell immunity against intracellular pathogens.
abstract: Immunity to intracellular microbial pathogens, including Chlamydia species, is controlled primarily by cell-mediated effector mechanisms, yet, the absence of antibodies results in inefficient microbial clearance. We investigated the hypothesis that certain Fc receptor functions promote the rapid induction of elevated T helper type 1 (Th1) response, which effectively clears chlamydiae. FcR(-/-) mice exhibited a delayed and reduced frequency of Chlamydia-specific Th1 cells, compared to FcR(+/+) mice. In vitro, antichlamydial antibodies increased the rate of Th1 activation by FcR(+/+) but not FcR(-/-) antigen-presenting cells. FcR(-/-) dendritic cells and the T cell-associated IgG2A and IgA mediate enhanced Th1 activation by antibodies. Immunization with chlamydia-antibody complexes induced elevated and protective Th1 response. These results provide a mechanistic basis for requiring both T cell and humoral immune responses in protective immunity and vaccine evaluation. Findings offer a paradigm in host defense wherein different effector components function indirectly to maximize the principal effector mechanism.
authors.affiliation: Morehouse School of Medicine, Atlanta, Georgia 30333, USA.
authors.forename: Terri
authors.initials: T
authors.lastname: Moore
authors.forename: Charles O
authors.initials: CO
authors.lastname: Ekworomadu
authors.forename: Francis O
authors.initials: FO
authors.lastname: Eko
authors.forename: LuCinda
authors.initials: L
authors.lastname: MacMillan
authors.forename: Kiantra
authors.initials: K
authors.lastname: Ramey
authors.forename: Godwin A
authors.initials: GA
authors.lastname: Ananaba
authors.forename: John W
authors.initials: JW
authors.lastname: Patrickson
authors.forename: Periakaruppan R
authors.initials: PR
authors.lastname: Nagappan
authors.forename: Deborah
authors.initials: D
authors.lastname: Lyn
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Black
authors.forename: Joseph U
authors.initials: JU
authors.lastname: Igietseme
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D002689:Chlamydia / Q000276:immunology; D002690:Chlamydia Infections / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D005260:Female; D017353:Gene Deletion; D005836:Genitalia, Female / Q000276:immunology / Q000382:microbiology; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D009092:Mucous Membrane / Q000276:immunology / Q000382:microbiology; D011961:Receptors, Fc / Q000235:genetics / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D011961:Receptors, Fc