The A1 (B) phenomenon: a monoclonal anti-B (BS-85) demonstrates low levels of B determinants on A1 red cells.
A monoclonal anti-B (BS 85) that reacts strongly with red cells from weak B variants (B3, Bint and Bv) has demonstrated the presence of a trace of B on A1 red cells. The agglutination of group A1 red cells by an anti-B antibody is called the A1 (B) phenomenon and is the converse of the B(A) phenomenon seen with certain monoclonal anti-A antibodies. Fragile A1 (B) agglutination is best seen by spin-tube techniques and A1 red cells negative in saline tests are agglutinated by albumin and protease enzyme-enhanced tests, but no reactions are seen with A2 red cells. The A1 (B) reaction is specifically inhibited by B substance, and D-galactose and the galactose-containing sugars melibiose and lactose. Red cells from B variants showed differential inhibition patterns with various sugars. A1 transferase levels were normal even in the strongest A1 (B) reactive blood samples, although the plasma H transferase levels and H status of these red cells were elevated. This is in contrast to the B(A) phenomenon which is associated with elevated levels of B transferase. It is suggested that A1(B) overlapping specificity can occur because of a combination of higher H activity (and thus more H sites) together with normal levels of A transferase activity as they are 20% higher than normal levels of B transferase. The production of anti-B reagents free of the A1 (B) phenomenon with BS-85 is achieved by suitable dilution using quality control tests with protease-treated A1 red cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Voak
D
D
Division of Transfusion Medicine, University of Cambridge, U.K.
Sonneborn
H
H
Yates
A
A
D000017:ABO Blood-Group System / Q000032:analysis*; D000116:Acetylgalactosamine / Q000378:metabolism*; D000418:Albumins / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D010450:Endopeptidases / Q000494:pharmacology; D005643:Fucose / Q000494:pharmacology; D005647:Fucosyltransferases / Q000378:metabolism; D005690:Galactose / Q000494:pharmacology; D005700:Galactosyltransferases / Q000378:metabolism*; D006386:Hemagglutination Tests; D006801:Humans; D007785:Lactose / Q000494:pharmacology; D008553:Melibiose / Q000494:pharmacology; D017350:N-Acetylgalactosaminyltransferases / Q000032:analysis; D012463:Saliva / Q000276:immunology; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013379:Substrate Specificity; D000097631:Galactoside 2-alpha-L-fucosyltransferase
D000017:ABO Blood-Group System; D000116:Acetylgalactosamine; D000418:Albumins; D000911:Antibodies, Monoclonal; D010450:Endopeptidases; D005643:Fucose; D005647:Fucosyltransferases; D005690:Galactose; D005700:Galactosyltransferases; D007785:Lactose; D008553:Melibiose; D017350:N-Acetylgalactosaminyltransferases; D000097631:Galactoside 2-alpha-L-fucosyltransferase; C003742:UDPgalactosamine-galactose acetylgalactosaminyltransferase; C023155:blood-group-substance alpha-D-galactosyltransferase