A cytotoxic monoclonal IgM antibody (Tü 101) directed against an antigenic determinant shared between the HLA-A allospecificities A2 and A28.

A complement-fixing murine monoclonal IgM antibody (TU 101) strictly directed against a supertypic determinant present on the HLA-A locus antigens A2 and A28 was defined from a fusion experiment employing T cell blasts as immunizing cells. The specificity of this antibody was established in the microcytotoxicity assay on 91 normal Caucasian blood donors, as well as in the SpA-Ig assay on a panel of lympho- and hematopoietic cell lines. TU 101 segregates only with its defined HLA allotypes in families. This reagent may be of particular value as a probe for analyzing a molecular relationship of different antigenic determinants on the HLA-A2 and A28 specificities in comparison with two recently defined anti-HLA-A2/A28 monoclonal antibodies and may help to characterize structural variations of these HLA-molecules on a serological and immunochemical basis.