title: CD16/32-specific biotinylated 2.4G2 single-chain Fv complexed with avidin-FITC enhances FITC-specific humoral immune response in vivo in a CD16-dependent manner.
abstract: Fcgamma receptors (FcgammaRs) play an essential role in the regulation of immune response due to their ability to bind immune complexes. Activating FcgammaRs may facilitate antigen presentation and dendritic-cell maturation, while in the late phase of the immune response, the inhibitory FcgammaRIIb may down-regulate B-cell activation upon cross-linking with activating receptors. In this study, we investigated the in vivo role of FcgammaRs on the modulation of humoral immune response. In order to get well-defined immune complexes that can bind to both the activating and the inhibitory FcgammaRs, we designed a mono-biotinylated single-chain fragment variable construct from the rat anti-mouse CD16/32 clone 2.4G2, linked to avidin-FITC, and tested its effect on the FITC-hapten-specific T-independent type 2 (TI-2) and T-dependent (TD) immune response. When injected intravenously in mice, the complex bound to a small portion of B220+, CD11b(high) and CD11c(high) cells and was localized in the spleen on marginal zone macrophages 15 min after treatment. When applied as a booster following primary immunization with TI-2 (FITC-dextran) or TD (FITC-keyhole limpet haemocyanin) antigens, the complex elevated the number of hapten-specific IgM/IgG-producing B cells. This effect was diminished in CD16KO mice, suggesting that the activating-type FcgammaRIII might be a key mediator of this mechanism.
authors: Department of Immunology, Eotvos Lorand University, 1117 Budapest, Hungary.
authors: Adrienn
authors: A
authors: Angyal
authors: Zsuzsanna
authors: Z
authors: Szekeres
authors: Péter
authors: P
authors: Balogh
authors: Zsuzsa
authors: Z
authors: Neer
authors: Eszter
authors: E
authors: Szarka
authors: Viktor
authors: V
authors: Virag
authors: David
authors: D
authors: Medgyesi
authors: Jozsef
authors: J
authors: Prechl
authors: Gabriella
authors: G
authors: Sarmay
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells / Q000187:drug effects / Q000276:immunology*; D001360:Avidin / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D019921:Biotinylation; D016207:Cytokines / Q000378:metabolism; D003911:Dextrans / Q000008:administration & dosage / Q000276:immunology; D016650:Fluorescein-5-isothiocyanate / Q000008:administration & dosage / Q000031:analogs & derivatives*; D006433:Hemocyanins / Q000008:administration & dosage / Q000276:immunology; D006825:Hybridomas; D056724:Immunity, Humoral / Q000187:drug effects; D007275:Injections, Intravenous; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011485:Protein Binding; D051381:Rats; D017452:Receptors, IgG / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology; D057127:Single-Chain Antibodies / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000276:immunology; D013997:Time Factors
chemical_list: D016207:Cytokines; D003911:Dextrans; C499172:Fcgr2b protein, mouse; C485700:Fcgr3 protein, mouse; D017452:Receptors, IgG; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; C015219:fluorescein isothiocyanate dextran; C036963:fluorescein isothiocyante avidin; D001360:Avidin; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin; D016650:Fluorescein-5-isothiocyanate