Macro- and Microdiíferences in Blood Group Antigens and Antibodies

Abstract

Evidence is presented that differences among serological specificities and in the structures of red cell antigens and antibodies fall naturally into two major categories, namely, macrodifferences and microdifferences. Examples are cited from the field of blood grouping, especially for the A-B-O, M-N, and Rh-Hr systems. It is demonstrated that macrodifferences usually relate to separate determinant groups in the antigen molecule, while sets of microdifferences may relate to one and the same determinant group, as with the cognate factors of Rh_o. To assume the existence of a one-to-one relationship between antibodies (and serological specificities) and determinant groups would require antigen molecules of finite size capable of accommodating an unlimited number of chemical determinant groups. It is pointed out that for each newly discovered specificity and antigen, it is important to determine whether one is dealing with a novel macro- or microdifference. The general applicability of the concept to fields other than blood grouping is pointed out.

Diversity of Human Anti-D Monoclonal Antibodies Revealed by Reactions with Chimpanzee Red Blood Cells

“…The reactivities of these antibodies, which depended on the agglu tination technique used, could be classified into four main types. system, it is built around a main antigen, called Rc, and closely related to the human Rh0(D) antigen [3,4], The chimpanzee isoimmune anti-Rc sera, properly absorbed with human blood, give results which parallel those ob tained with human anti-D antisera [5,6], It is likely that both chimpanzee Rc and human Rh"(D) are the products of two genes that derived from a common ancestor [7], Five other antigens of the R-C-E-F blood group system, defined by chimpanzee isoimmune reagents, namely: anti-Cc. -Ec, -Fc, -cc, -cch constitute exclusive attributes of chimpanzee RBCs and do not have any counterparts in the human Rh blood group system.…”