The immune adherence receptor: dissociation between the expression of erythrocyte and mononuclear cell C3b receptors.

Human erythrocytes have a surface receptor for the third component of complement (C3b). This receptor mediates the immune adherence (IA) reaction. In this study, erythrocytes from over 100 normal donors and from donors with rare blood group types were examine for IA reactivity. All donors had red cells with high titer IA activity, with the exception of one Rh null individual whose erythrocytes had barely detectable IA activity. Five other Rh null donors had normal IA titers. Because of the apparent defect in the expression of the red cell C3b receptor in this one individual, the mononuclear cell C3b receptors of this donor were studied and found to be normal. These findings suggest that expression of the erythrocyte C3b receptor may be controlled by factors which differ from those determining expression of the mononuclear cell C3b receptor.