The B3 phenotype in Chinese.

Sixteen cases of subgroup B3 and two cases of subgroup A1B3 were found among donated blood processed in Taipei Blood Donation Center. The frequencies of B3 and of A1B3 among group AB Chinese in Taiwan are about 1 in 900, and about 1 in 1800, respectively. The B3 red cells showed 1 to 2+ mixed field agglutination with anti-B, 2 to 3+ mixed field agglutination with anti-A, B, and 4+ agglutination with anti-H. Reverse grouping showed anti-A but no anti-B activity; saliva of secretors contained B and H substances. The significant low avidity of subgroup B3 and subgroup A1B3 red cells with both polyclonal and monoclonal antiserums, as compared with normal group B cells, coupled with the difference in the avidity of the reaction between monoclonal and polyclonal antisera with B3 and A1B3 red cells, suggest the possibility of a qualitative as well as a quantitative difference in the B antigen of B3 red cells.