title: Immune complex and Fc receptor-mediated augmentation of antigen presentation for in vivo Th cell responses.
abstract: It has recently been established that FcRs are involved in the triggering of type II and III inflammatory responses. Although FcR is not believed to be involved in the regulation of T cell function, the in vivo contribution of FcRs to T cell function still remains unclear. We analyzed in vivo responses of delayed-type hypersensitivity and proliferation of CD4+ T cells to Ags in FcRgamma-/- mice lacking the expression and function of FcgammaRI, FcgammaRIII, and FcepsilonRI. We found that the delayed-type hypersensitivity response in FcRgamma-/- mice is significantly decreased compared with that in wild-type mice. Moreover, the secondary responses of proliferation and cytokine production as well as the Ab formation by CD4+ T cells from FcRgamma-/- mice to Ag and normal APCs were also reduced. In contrast, in vitro primary T cell proliferative responses upon stimulation with anti-TCR Ab or MLR as well as in vivo primary response against staphylococcus enterotoxin B administration were not different between T cells from FcRgamma-/- and wild-type mice. In addition, the Ag presentation function of APCs from unimmunized FcRgamma-/- mice was normal. On the other hand, Ab-deficient mice also revealed impaired T cell responses. These results demonstrate that the defective T cell responses in FcRgamma-/- mice were due to impaired Ag presentation during in vivo priming not to a defect in T cells. Therefore, they suggest that the FcRs on APCs mediate efficient priming of Th cell responses in vivo in an immune complex-dependent manner.
authors.affiliation: Department of Molecular Genetics, Chiba University Graduate School of Medicine, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hamano
authors.forename: H
authors.initials: H
authors.lastname: Arase
authors.forename: H
authors.initials: H
authors.lastname: Saisho
authors.forename: T
authors.initials: T
authors.lastname: Saito
mesh_terms: D000276:Adjuvants, Immunologic / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D000936:Antigen-Antibody Complex / Q000502:physiology*; D004306:Dose-Response Relationship, Immunologic; D006968:Hypersensitivity, Delayed / Q000235:genetics / Q000276:immunology; D007108:Immune Tolerance / Q000235:genetics; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017452:Receptors, IgG / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000378:metabolism*
chemical_list: D000276:Adjuvants, Immunologic; D000936:Antigen-Antibody Complex; D017452:Receptors, IgG