CHARACTERIZATION OF BLOOD-GROUP-ACTIVE ERYTHROCYTE-MEMBRANE GLYCOPROTEINS WITH HUMAN ANTISERA

Antisera to high- and low-incidence blood-group antigens were used in immunoblotting and immune precipitation studies to identify novel eryt hrocyte membrane components and to assign antigens to known proteins. Several antibodies identified well-characterized membrane proteins whi ch are widely expressed on other cells and tissues. The Cromer system antigens were found to reside on the complement regulatory protein dec ay accelerating factor (DAF). Antigens of the Indian collection were l ocated to the cell adhesion molecule, CD44. The Cartwright system anti gens were assigned to acetylcholinesterase, the function of which, on erythrocytes, remains unclear. Two novel blood-group-active glycoprote ins were identified. One carries the Scianna system antigens whilst th e second carries the high-incidence antigens, Gy(a), Hy and Jo(a). The low-incidence antigens, Dh(a) and Rd, were assigned to Glycophorin C and to the Scianna-active glycoprotein, respectively. The existence of Cromer-null, DAF-deficient erythrocytes greatly facilitated the study of the function of DAF on erythrocytes. Location of the YT locus and hence of the AChE gene to chromosome 7q22 may be of significance in le ukaemias and myelodysplasias since this region is a mutational 'hot sp ot' in these disorders. The novel proteins identified, for which no mo noclonal antibodies are available, may also prove to be of functional significance on erythrocytes or on other cells and tissues. Several of the rare phenotype cells, such as the In(a - b -) cells, Gy(a -) cell s and the Sc-null cells, may prove to be of great value in defining th e function of these molecules on erythrocytes, in the way that Inab ce lls have been for studying the function of DAF.