Studies on the Binding of IgG and F(ab) Anti-A to Adult and Newborn Group A Red Cells

. The values of the functional affinity constants for the binding of human IgG anti-A and its F(ab) derivative with adult and newborn group-A red cells have been determined. The values obtained for both monovalent and bivalent antibody with both types of cells were of the same order (about 1times108M-1), indicating that IgG anti-A binds to red cells only by one of its F(ab) arms.