A structural model for 30 Rh D epitopes based on serological and DNA sequence data from partial D phenotypes

Detection of Rh23 in the partial D phenotype associated with the DVa category

“…The low‐frequency antigen, Rh23 (D w ), is characteristic of the D Va category 1 . The D Va red cell (RBC) is also characterized as being negative when tested with monoclonal antibodies (MoAbs) to epitopes D1 and D5 in the 9‐epitope model 2 …”

CHO expression of a novel human recombinant IgG1 anti-RhD antibody isolated by phage display

“…However, the calculated pI value of MDJ8s was 8´96 indicating that, despite bromelin treatment to reduce the negative charge on RBCs, the interaction still selects for cationic antibodies. The hydropathy model for the RhD antigen predicts a transmembrane protein with six extra-cellular loops where exon 5 codes for amino acids in loop 4 (Le van Kim et al, 1992;Scott et al, 1996). Whereas the D VI variants result from conversion events involving exons 3±6 of the Rh CE gene, the Rh 33 variant encodes only D-specific amino acids resulting from exon 5 of the RhD gene with the remaining amino acids resulting from Rh CE exons (Beckers et al, 1996;Wagner et al, 1998).…”

Sequence and Specificity Analysis of Recombinant Human Fab Anti–Rh D Isolated by Phage Display

“…Furthermore, a recent new method for processing hyperimmune anti–Rh D plasma relies on the high isoelectric point of the anti–Rh D antibodies which are preferentially retained on a cation exchange column such that a considerable enrichment of specific anti–Rh D antibodies is obtained [42]. Taken together with the sequence comparisons these facts seem to indicate an oligoclonal response to the Rh D antigen which would be in agreement with the probable restricted surface topology of the Rh D antigen [11, 41]. …”

“…Both libraries were panned on fresh whole RBC since the Rh D antigen, an integral membrane protein of 417 amino acids [8], loses its immunogenicity during purification [9] and is not suitable for commonly used solid phase selection procedures [10]. Hydropathy studies suggest that the Rh D antigen has 12 bilayer spanning domains with only very short connecting regions extending outside the cell membrane or protruding into the cytoplasm [8, 11]. Thus the parts of the Rh D antigen visible to antibodies are relatively restricted and may be under conformational constraint.…”

“…The majority of partial D phenotypes arise by gene conversion events between the Rh D and Rh C E exons or point mutations [15]. More recently using panels of human monoclonal anti–Rh D antibodies a 30–epitope model has been proposed to define the different partial D categories [11, 16, 17, 18]. …”