Evidence that CDw108 membrane protein bears the JMH blood group antigen

BACKGROUND: CDw108 is a cluster‐of‐differentiation antigen that resides on a glycosylphosphatidylinositol (GPI)‐linked protein; it has not previously been shown to be expressed on red cells. JMH is a high‐ frequency red cell blood group antigen that resides on a GPI‐linked protein of molecular weight similar to that bearing CDw108. The purpose of this study was to investigate whether CDw108 is expressed on red cells and whether it resides on the same membrane protein as does JMH. STUDY DESIGN AND METHODS: Murine monoclonal antibodies to CDw108, MEM‐ 121 and MEM‐150, as well as a murine monoclonal antibody and human antibodies to JMH were used in radioimmunoassay, inhibition assay, Western blotting, and monoclonal antibody‐specific immobilization of erythrocyte antigen assay. RESULTS: MEM‐121 and MEM‐150 were found to bind to red cells, and MEM‐150 blocked binding of human anti‐JMH to red cells. Anti‐CDw108 and anti‐JMH identified red cell membrane proteins that were of similar size and that were absent from JMH‐negative red cells on Western blotting. MEM‐150 and MEM‐121 also immobilized the same protein that reacted with human anti‐JMH. CONCLUSION: CDw108 is expressed on red cells and resides on the same GPI‐linked membrane protein as does the JMH blood group antigen.