THE RH ANTIGEN-D - PARTIAL D-ANTIGEN AND ASSOCIATED LOW INCIDENCE ANTIGENS

The expression of the Rh antigen D varies quantitatively and qualitati vely (partial D); published information and 15 years' work studying D variants are discussed in this review D epitopes correspond to the rea ction patterns of monoclonal anti-D with partial D antigens. Partial D antigens can be reported in terms of their D epitopes but the epitope profile of cells with a quantitative variant of D (weak D) is difficu lt to determine reliably by haemagglutination tests. Nine partial D an tigens, categories II-VII, DFR and two not previously reported, are id entified by their epitope profiles and by association with low inciden ce antigens. Monoclonal anti-D recognize 16 D epitopes and more epitop es are anticipated. The specificities of polyclonal anti-D made by peo ple with partial D antigens are considered in terms of possible D epit ope specificities: recognized epitope specificities, or combination th ereof, were not able to account for all observed reaction patterns of anti-D made by immunized individuals with partial D phenotypes. An att empt is made to understand partial D antigens and their associated low incidence antigens in terms of the molecular genetic information avai lable.