A monoclonal antibody, HLAO1, was prepared by immunizing BALB/c mice with human lymphocytes of known HLA genotype. The monoclonal antibody is cytotoxic, of the IgG 2b isotype and binds to a protein of Mr 43,000 noncovalently associated with the beta 2-microglobulin. Genetic analysis proved complete concordance in the expression of the antigenic determinant defined by this monoclonal antibody and the presence of a supertypic (public) antigen, the HLA-Bw4. As expected, the monoclonal antibody also reacted with the antigens of HLA-A locus, A23, A24, and A32. The computer analysis of HLAO1 antibody binding to the Bw4/Bw6 heterozygous lymphocytes gave the approximate number of antigenic determinants, n = 2.2 X 10(4)/cell, and Ka = (5.9 +/- 0.8) X 10(9) M-1. Besides its potential immunochemical applications, the HLAO1 monoclonal antibody can become a useful tool in routine cytotoxicity typing of HLA antigens on peripheral lymphocytes.

Institute of Molecular Genetics Czechoslovak Academy of Sciences Prague

Quantitative estimation of HLA-A and HLA-B antigens carrying the Bw4 supertypic specificity in human peripheral blood lymphocytes