Characterization of an antibody specific for HLA-A36 and not reactive with HLA-A1

Humoral sensitization to HLA often results in antibodies to public determinants shared among two or more antigens. Although monoclonal antibodies to A36 have been produced, there are no reports of polyclonal antibodies that react with A36 but not A1. We report here sera from a heart transplant recipient that reacted with A36 but not A1 in tests with both phenotype and single antigen panels on the Luminex platform. Flow cytometric crossmatch tests yielded positive results with an A36 bearing phenotype but not with a phenotype containing A1. A36 reactivity in solid phase assays was abrogated by absorption with cells bearing A36, but not with A1-positive cells. The frequency of B cells in this patient specific for A1 was comparable to that for individuals not sensitized to A1. These data indicate that reactivity was to an epitope present on A36 but absent from A1.