Multiple epitopes recognised by human monoclonal IgM anti-D antibodies.
Bivalent 7S subunits were obtained from 7 purified IgM human monoclonal anti-D antibodies with 33-63% of the total protein-retaining functional binding activity. The number of sites per red cell recognized by these subunits ranged between 9,400 and 28,500. The values are taken to indicate that a number of different epitopes on the D polypeptide are being recognized. There was competition between IgG and IgM antibodies for binding to the red cells, indicating that both classes of antibody are recognizing epitopes on the same D polypeptide. The value of the functional affinity constants for the binding of the 7S subunits varied between 1.0 and 8.8 x 10(7) M-1 and there was a 3- to 16-fold increase on reduction of the ionic strength (0.05 M NaCl). Using agglutination in microwells, the end-point of the titres for the native pentamer IgM antibodies occurred at concentrations in the range 7-26 ng/ml, with one exception where the concentration required was 165 ng/ml.
MRC Molecular Immunopathology Unit, AFRC Cambridge Research Station, Babraham, UK.
N C
NC
Hughes-Jones
B D
BD
Gorick
D
D
Beale
D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology*; D001666:Binding Sites, Antibody / Q000276:immunology; D000939:Epitopes / Q000032:analysis*; D006386:Hemagglutination Tests; D006801:Humans; D007075:Immunoglobulin M / Q000737:chemistry / Q000276:immunology*; D012204:Rh-Hr Blood-Group System / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D007075:Immunoglobulin M; D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen