Immunochemical Characterization of the Rh C^w Antigen Using Human Monoclonal Antibodies

Abstract

Background and objectives: Human monoclonal antibodies have been produced against various Rh antigens. We report here the production of another one against Rh C^w and the first such antibody against Rh C^w. Materials and methods: Two heterohybridomas secreting lgG human monoclonal antibodies against Rh C^w and Rh C (MS-353 and MS-242 respectively) were produced from alloimmunized donors. Their specificity was confirmed by serological testing. Results: MS-353 reacted with all C^w -positive phenotypes but not with any Cwnegative phenotypes, whereas MS-242 reacted with all C^w-positive and C-positive phenotypes. Using ^125 -labelled antibodies, the average number of C^w sites/ red cell was 32,000 (R(1)^w R(1)^w), 15,200 (R(1) ^w R(2)), 19,800 (R(1)^W R(2)), 15,300 (R(1) ^wr), 26,200 (r ^w r), and the average number of C sites per red cell on equivalent C^w/Cpositive phenotypes was similar: 22,400 (R(1) R(1)), 21,800 (R(1) ^w R,), 12,300 (R(1) R(2)), 11,700 (R(1) ^wR(2), 13,400 (R,r), 15,100 (R(1) ^wr), 21,100 (r'r), 18,700 (r ^wr). MS-353 and MS-242 were mutually inhibitory. Both antibodies specifically immunoprecipitated a 33- to 34-kD polypeptide from l2:T-surface-labelled cells. Conclusion: MS-353 is suitable for the serological detection of C^w -positive cells, and the immunochemical data are entirely consistent with the report that the C^w antigen is associated with a point mutation in the RHCE gene [Blood, 1995;86:1196 1201],