Interaction of human erythrocyte glycophorin with immunoglobulins G

We have found that human glycophorin and asialoglycophorin interacted with human non-immune IgG. To characterize quantitatively the interaction between glycophorin and IgG we elaborated a direct solid-phase radioimmunoassay. We showed that the binding of IgG was reversible and saturable within the range of IgG concentrations used. Glycophorin bound higher amounts of aggregated than non-aggregated immunoglobulins. The apparent association constant for non-aggregated human IgG was 5.45 +/- 0.93 x 10(5) M-1 and 1.13 +/- 0.78 x 10(6) IgG molecules were bound per 1 picogram of the glycophorin. The binding of glycophorin occurs within the F(ab)2 fragment of IgG, mainly.