Intravenous Immunoglobulins Suppress Antibody-Dependent Effector Functions of Human Peripheral Blood Cells

Abstract

RationaleSeveral studies have shown the importance of self-reactive antibodies in the maintenance of autoimmune diseases. Therefore, we asked whether IGIV, which is therapeutically effective in some of those diseases, directly modulates antibody-mediated effector functions.MethodsWe used a human in vitro system to analyze potential modulatory effects of IGIV on effector functions in antibody-dependent cellular cytotoxicity (ADCC). Human peripheral blood mononuclear cells (PBMC) from 47 healthy volunteers were pre-incubated with IGIV and then added to human breast cancer cells (SK-BR3) opsonized with a specific antibody. The cytotoxic damage to SK-BR3 cells was determined by measuring lactate dehydrogenase release into supernatants. IGIV-mediated effects on viability and Fc gamma receptor (FcγR) expression of PBMC were analyzed by flow cytometry.ResultsPre-incubation of PBMC with IGIV for 48h resulted in a marked inhibition of ADCC, ranging from 15% to 74% (mean 42%) which could not be mimicked with human monoclonal IgG1 and IgG2 antibodies. Flow cytometric analysis indicated that IGIV induced natural killer (NK) cell death, which significantly correlated with ADCC inhibition. The IGIV-induced decrease in NK cell viability was not triggered by FcγR ligation since the addition of FcγR blocking antibodies could not prevent cell death induction. Furthermore, IGIV enriched for sialic acid bearing glycans by lectin affinity chromatography with Sambucus nigra agglutinin showed no differences in the effects on NK cell viability and ADCC compared with non-enriched IGIV.ConclusionsIGIV modulates antibody-dependent effector functions of human immune cells, which could contribute to the modulatory activities of IGIV in inflammatory and autoimmune diseases. RationaleSeveral studies have shown the importance of self-reactive antibodies in the maintenance of autoimmune diseases. Therefore, we asked whether IGIV, which is therapeutically effective in some of those diseases, directly modulates antibody-mediated effector functions. Several studies have shown the importance of self-reactive antibodies in the maintenance of autoimmune diseases. Therefore, we asked whether IGIV, which is therapeutically effective in some of those diseases, directly modulates antibody-mediated effector functions. MethodsWe used a human in vitro system to analyze potential modulatory effects of IGIV on effector functions in antibody-dependent cellular cytotoxicity (ADCC). Human peripheral blood mononuclear cells (PBMC) from 47 healthy volunteers were pre-incubated with IGIV and then added to human breast cancer cells (SK-BR3) opsonized with a specific antibody. The cytotoxic damage to SK-BR3 cells was determined by measuring lactate dehydrogenase release into supernatants. IGIV-mediated effects on viability and Fc gamma receptor (FcγR) expression of PBMC were analyzed by flow cytometry. We used a human in vitro system to analyze potential modulatory effects of IGIV on effector functions in antibody-dependent cellular cytotoxicity (ADCC). Human peripheral blood mononuclear cells (PBMC) from 47 healthy volunteers were pre-incubated with IGIV and then added to human breast cancer cells (SK-BR3) opsonized with a specific antibody. The cytotoxic damage to SK-BR3 cells was determined by measuring lactate dehydrogenase release into supernatants. IGIV-mediated effects on viability and Fc gamma receptor (FcγR) expression of PBMC were analyzed by flow cytometry. ResultsPre-incubation of PBMC with IGIV for 48h resulted in a marked inhibition of ADCC, ranging from 15% to 74% (mean 42%) which could not be mimicked with human monoclonal IgG1 and IgG2 antibodies. Flow cytometric analysis indicated that IGIV induced natural killer (NK) cell death, which significantly correlated with ADCC inhibition. The IGIV-induced decrease in NK cell viability was not triggered by FcγR ligation since the addition of FcγR blocking antibodies could not prevent cell death induction. Furthermore, IGIV enriched for sialic acid bearing glycans by lectin affinity chromatography with Sambucus nigra agglutinin showed no differences in the effects on NK cell viability and ADCC compared with non-enriched IGIV. Pre-incubation of PBMC with IGIV for 48h resulted in a marked inhibition of ADCC, ranging from 15% to 74% (mean 42%) which could not be mimicked with human monoclonal IgG1 and IgG2 antibodies. Flow cytometric analysis indicated that IGIV induced natural killer (NK) cell death, which significantly correlated with ADCC inhibition. The IGIV-induced decrease in NK cell viability was not triggered by FcγR ligation since the addition of FcγR blocking antibodies could not prevent cell death induction. Furthermore, IGIV enriched for sialic acid bearing glycans by lectin affinity chromatography with Sambucus nigra agglutinin showed no differences in the effects on NK cell viability and ADCC compared with non-enriched IGIV. ConclusionsIGIV modulates antibody-dependent effector functions of human immune cells, which could contribute to the modulatory activities of IGIV in inflammatory and autoimmune diseases. IGIV modulates antibody-dependent effector functions of human immune cells, which could contribute to the modulatory activities of IGIV in inflammatory and autoimmune diseases.