Serologically defined Rh determinants.

Forty-six numbered Rh antigens which are detected in serological tests are extant; antigens which were most recently numbered are of high or of low incidence. The identification of high incidence Rh antigens through studies involving cells with rare Rh phenotypes, including Rhnull cells, is described briefly. The serological investigations and family studies required to show that a low incidence antigen is an Rh antigen are illustrated by a description of the JAL (Rh48) antigen. Heterogeneity of polymorphic Rh antigens revealed by using monoclonal antibodies (MABS) is demonstrated by consideration of the Rh antigen D. A summary of results of serological tests shows that monoclonal anti-D antibodies define eight D epitopes. Partial D antigens of the D categories are reassessed in terms of expression of D epitopes.