Characterization of the blood group Kell (K1) antigen with a human monoclonal antibody.
A human monoclonal anti-Kell (K1) antibody secreted by an Epstein-Barr virus (EBV)-transformed B-cell line was used for binding studies and immunopurification of the K1 blood group antigen. The 125I-labeled antibody bound to 4 to 5 x 10(3) and 2.5 to 3 x 10(3) antigenic sites on K1K1 and K1K2 erythrocytes, respectively, with an affinity constant of 5 x 10(8) mol/L-1. Immunoprecipitation analysis showed that the K1 antigen is carried by a 93 Kd glycoprotein containing several cysteine residues, and approximately six N-glycosidically linked sugar chains but no detectable O-linked sugar. A minor labeled component of 32 Kd was also immunoprecipitated from K1K1 RBCs but the 93- and 32-Kd components were absent from K2K2 and Kell null erythrocytes. Under nonreducing conditions, three bands were detected at 200 (weak), 120, and 93 Kd. We suggest that the 120-Kd component represents a heterodimer of the 93- and 32-Kd proteins covalently linked by disulfide bridge(s). The 93-Kd glycoprotein is a transmembrane component which interacts with the membrane skeleton but is distinct from band 3 as shown by one-dimensional peptide mapping. The site density of K1 antigen blood group on Gerbich-negative RBCs (Ge:-2,-3) was threefold lower than on K1K1 erythrocytes, but the qualitative properties of the 93-Kd component were not modified.
Jaber
A
A
Institut National de Transfusion Sanguine, Paris, France.
Blanchard
D
D
Goossens
D
D
Bloy
C
C
Lambin
P
P
Rouger
P
P
Salmon
C
C
Cartron
J P
JP
D000596:Amino Acids / Q000032:analysis; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000915:Antibody Affinity; D000918:Antibody Specificity; D001667:Binding, Competitive; D001789:Blood Group Antigens / Q000276:immunology*; D006601:Hexoses / Q000032:analysis; D006801:Humans; D007626:Kell Blood-Group System / Q000032:analysis / Q000276:immunology*; D008970:Molecular Weight; D010449:Peptide Mapping; D011233:Precipitin Tests
D000596:Amino Acids; D000911:Antibodies, Monoclonal; D001789:Blood Group Antigens; D006601:Hexoses; D007626:Kell Blood-Group System