A common epitope between HLA-B27, -B13 and -B37 alloantigens defined by a monoclonal antibody

An anti-HLA-B27 monoclonal antibody produced by the hybridoma technique is described. This BD.7 reagent is a cytotoxic IgM antibody. Its reactivity was studied by lymphocytotoxicity tests, indirect immunolfluorescence tests and biochemical analysis against an extensive panel of peripheral blood mononuclear cells. All HLA-B27 positive samples, either from normal subjects or from patients with Ankylosing Spondylitis, were recognized by this reagent. Moreover, a cross-reaction was observed with HLA-B13 cells, and a new unexpected reaction with all HLA-B37 cell suspensions. The interest of such a reagent is discussed.