title: Quantitation of D sites on selected 'weak D' and 'partial D' red cells.
abstract: Measurements have been made of the number of available sites on 10 examples of red cells in which the only abnormality appeared to be a quantitative reduction in the expression of D (weak D cells); these estimates were carried out using three monoclonal anti-D antibodies, Fog-1, Brad-3 and Los-2. The values varied with the monoclonal antibody that was used and fell within the range of 170-1,870 sites/cell. A further 3 examples of weak D cells which had brought about immunisation following transfusion were found to have between 390 and 1,470 sites per red cell. The implications of the D site density on the immunogenicity of weak D cells are discussed. The number of sites on red cells with structurally abnormal D (partial D cells) were also estimated, using the antibody Fog-1. Four of the 5 examples of cells of category IVa (probable phenotype Ror) were found to have a high expression of D (range 29,300-41,300), but the available D sites of categories DVa, DVIa, and DVII were considerably reduced (< 500, < 500 and 2,400-7,500 sites/cell, respectively). As a working hypothesis, it is suggested that there are two types of genetic abnormality leading to an abnormal expression of D. First, a defect in genomic DNA leading only to a quantitative reduction in the number of available D sites; this genomic lesion should be termed 'weak D'. Secondly, genomic defects leading to amino acid sequence abnormalities and structural change in the D polypeptide; these lesions should be collectively known as 'partial D'.
authors.affiliation: MRC Immunopathology Unit, MRC Centre, Cambridge, UK.
authors.forename: B
authors.initials: B
authors.lastname: Gorick
authors.forename: D C
authors.initials: DC
authors.lastname: McDougall
authors.forename: W H
authors.initials: WH
authors.lastname: Ouwehand
authors.forename: M A
authors.initials: MA
authors.lastname: Overbeeke
authors.forename: P
authors.initials: P
authors.lastname: Tippett
authors.forename: N C
authors.initials: NC
authors.lastname: Hughes-Jones
authors.forename: D J
authors.initials: DJ
authors.lastname: van Rhenen
mesh_terms: D000911:Antibodies, Monoclonal; D000939:Epitopes; D004912:Erythrocytes / Q000276:immunology*; D006801:Humans; D010455:Peptides / Q000097:blood*; D010641:Phenotype; D012204:Rh-Hr Blood-Group System / Q000097:blood*
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D010455:Peptides; D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen