A critical study of the IgG subclasses of Rh anti-D antibodies formed in pregnancy and in immunized volunteers.

Abstract

The IgG subclasses of Rh anti-D antibodies were investigated in a hundred anti-Rh sera using IgG subclass-specific antisera. Antibody activity was found to be entirely restricted to the IgG1 and IgG3 subclasses. Immunized volunteers tended to produce both IgG1 and IgG3 antibodies whereas antibodies from incompatible pregnancies were more often composed of only one subclass. It is suggested that some supposedly subclass `specific' antiglobulin sera that have been standardized using weakly coated test red blood cells may show cross-reaction with more strongly coated cells and this may lead to the erroneous assumption that certain high titre anti-Rh sera also contain IgG2 and IgG4 antibodies.