Normal individuals with an HLA haplotype containing either DR2, MT1, or B8/DR3 are more likely to have abnormally prolonged Fc receptor-mediated mononuclear phagocyte system (MPS) clearance of IgG-sensitized autologous erythrocytes than their normal counterparts without such haplotypes. Although measurement of Fc receptor binding by rosette formation and saturable IgG aggregate binding revealed no differences among groups, Fc receptor-mediated phagocytosis of IgG-sensitized bovine erythrocytes by monocytes was decreased in the DR2-positive and MT1-positive individuals. The basal in vivo MPS clearance in normal individuals may be immunogenetically determined and may reflect differences in phagocytic rates.

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