CHARACTERIZATION OF 2 HUMAN-IGM MONOCLONAL-ANTIBODIES REACTIVE WITH HLA-B27

We describe here the generation and characterization of two human mono clonal IgM antibodies (UL-4F11 and UL-F6) reactive with HLA-B27. The m onoclonal antibody (mAb) UL-4F11 is cytotoxic for peripheral mononucle ar cells and, therefore, useful as typing reagent for HLA-B27 and HLA- B38. Protein chemistry showed that the mAb UL-4F11 precipitates HLA-B2 7 molecules. Epitope mapping analysis suggests that the amino acids 45 , 67, 82 and 83 (alpha-1 domain) of the HLA-B27 sequence are necessary for mAb UL-4F11 reactivity. The mAb UL-F6 is suitable for complement dependent lysis of lymphoblastoid cell lines and stimulated peripheral blood mononuclear cells with HLA-B27 (B 2701, B*2702, B*2703, B*2705 , B2707), B13, B40 (60,61), B47 and B48 specificities. Its reactivity indicates that the amino acid valine in position 152 and glutamic aci d in position 163 of the alpha-2 domain are crucial for the binding ep itope.