Competition between ABO and Le Gene Specified Enzymes

Abstract

Radioimmunoassays were prepared using two anti-A and one anti-B reagents. The specificity of the procedures was assessed with 13 artificial antigens. The amounts of A and B natural antigens in saliva of ABH secretors of known Lewis phenotype were measured with these assays. The results confirmed that the average amount of A antigen is lower in Lewis-positive (Le^b) than in Lewis-negative (Le^d) donors and in A(2) than in A(1) donors. However, the differences among the four combined A and Lewis phenotypes were only supported by significantly lower amounts of A antigenic determinants in A(2)Le^b as compared to the other three phenotypes (A(1)Le^b, A(1)Le^d and A(2)Le^d) that had similar amounts of A antigenic determinants. No Lewis-related difference could be detected in the amounts of B antigens between BLe^b and BLe^d donors. The results are discussed in terms of competition between A, B and Lewis-gene-specified enzymes for their common acceptors. The difference in the efficiency of the A(2) enzyme as compared to that of the A(1) enzyme is proposed as a possible explanation for the A(1)-A(2) phenotypic difference.