Monoclonal antibody (Tü48) defining alloantigenic class I determinants specific for HLA-Bw4 and HLA-Aw23,-Aw24 as well as -Aw32.

A monoclonal antibody (Tü48) was prepared against human lymphocytes. Immunochemical analysis indicated that Tü48 binds to a fraction of HLA molecules. Tü48 was tested on 398 HLA-A,B,C/DR-typed normal blood donors in the microcytotoxicity assay and was found to detect a "supertypic" determinant on molecules bearing the HLA specificities -Bw4, Aw23(9), -Aw24(9), and -Aw32. Among the HLA-Bw4-positive individuals, negative or weak reactivity of Tü48 was found with about one-fourth of normal donors heterozygous for the HLA antigen Bw44. This points to the possibility that the antigenic determinant detected by Tü48 is not expressed on all HLA-molecules carring the HLA-Bw4 specificity on the cell surface. Alternatively, weak or no expression of the Tü48 antigenic determinant on some HLA-Bw44 bearing molecules might be explained by the existence of molecular variants of glycoproteins with this HLA specificity. The concept of "supertypic" HLA specificities is discussed with regard to the expression of a monoclonal antibody-defined epitope on both certain HLA-A and B molecules.