Purification and characterization of an erythrocyte membrane protein complex carrying Duffy blood group antigenicity. Possible receptor for Plasmodium vivax and Plasmodium knowlesi malaria parasite

Abstract

A murine monoclonal antibody, named anti-Fy6, which agglutinates all human red cells except those of Fy(a-b) phenotype was used for purification and characterization of Duffy antigens. Duffy antigens are multimeric red cell membrane proteins composed of different subunits of which only one, designated pD protein, reacts in immunoblots with the murine monoclonal antibody anti-Fy6. Affinity-purified detergent-soluble antigen-antibody complex obtained from red cells, surface-labeled with 125I yielded a complex pattern of bands when separated by polyacrylamide gel electrophoresis. Proteins that react with anti-Fy6 in immunoblots are: pA and pB (greater than 100 kDa) and pD (36-46 kDa). Electroeluted pD protein aggregates and generates bands of similar molecular mass to pA and pB proteins. Electroeluted pA and pB proteins disaggregate yielding pD protein. Oligomers and monomers of pD protein are present in red cells carrying Duffy antigens and absent in Fy(a-b-) cells. Six other proteins of molecular weight ranging from 68 to 21 kDa either associate or co-purify with pD protein. These proteins are only present in Duffy antigen positive cells. The pD protein is different in Fy(a+b-) and Fy(a-b+) cells by fingerprint analysis. Human antisera identify the same proteins in red cell carrying Duffy antigens as the murine monoclonal antibody anti-Fy6.