Sera containing Rh antibodies were taken from Rh-negative women at intervals during pregnancy and postpartum. A selection of these was fractionated on DEAE cellulose and by density gradient ultracentrifugation.
The distribution among the immunoglobulin fractions γSS, γ1A, and γ1M of Rh antibodies in the sera of Rh-negative women during pregnancy was analysed by these fractionation procedures and also by treatment with 2-mercaptoethanol and by testing with rabbit antisera prepared against purified immunoglobulin fractions.
The experiments showed that incomplete Rh antibodies occurred in the 7SS-, γ1A-, and γ1M-globulin fractions, although the bulk of the antibody was in the 7SS. In addition, evidence that the previously described (13) "papain-type" antibody is an incomplete γ1M-globulin is presented.
