Rh antibodies detectable only by enzyme technique

The titration of Rh antibodies at intervals during pregnancy by various methods has led to evidence for the existence of an Rh antibody or antibodies detectable by an enzyme (papain) method but not by anti-human-globulin. Adsorption experiments show that this antibody is less readily absorbed by red cells than the other Rh antibodies unless the cells are pretreated with enzyme. This fact may possibly account for the finding of a negative or weakly positive anti-human-globulin test associated with moderate or high titres by enzyme techniques. The relationship of this antibody to the general immunization process in pregnant women is discussed.