Modulation of Human B-Lymphocyte Receptors for IgG Does Not Affect HLA-DR Antigens

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Abstract
Receptors for the Fc portion of immunoglobulin G (FcγR) on the surface of human peripheral T cells can be modulated on contact with antigen-antibody immune complexes (IgG-IC). Our results demonstrate that the FcγR present on the surface of human B cells are also modulated on exposure to IgG-TC. Furthermore, the expression of HLA-DR molecules is not affected by the TgG-IC-induced disappearance of FcγR. In fact, the percentage of HLA-DR-positive cells and the relative amount of HLA-DR molecules on individual B cells analysed by flow microfluorometry was shown not to be influenced by FcγR modulation. Moreover, pretreatment of cells with monoclonal antibodies directed against non-polymorphic determinants of HLA-DR antigens did not prevent the binding of IgG-coated ox erythrocytes. These results argue against a structural relationship between FcγR and HLA-DR molecules on the surface of the B-cell populations investigated here.