Local analysis of HLA class II monoclonal antibodies (mAb) proposed for prescreening for the 11th International Histocompatibility Workshop

Production and characterization of murine monoclonal antibodies recognizing HLA-DQ polymorphisms obtained by immunizing mice with transfected L cells

Two polymorphic anti-HLA-DQB1 mAbs, TM 902 and TM 903, have been produced by immunizing F1 mice (Balb/C x C3H) with HLA-DQ-transfected mouse L cells. Cytotoxic analysis on a panel of HLA-typed cell lines has shown that TM 902 reacts with all the DQB1* alleles except DQB1*0501, *0502, and *0503, and DQB1*0601, *0602, *0603, and *0604, whereas TM 903 reacts with the DQB1*0501, *0502, and *0503, DQB1*0601, *0602, *0603, and *0604, and DQB1*0401 and *0402 alleles. The same reactivity pattern has been confirmed by cytofluorimetric analysis. Indirect immunofluorescence with various class-II-transfected cell lines showed no binding of both mAbs to the DR or DP products, suggesting their reactivity to the DQ products. The use of transfectants expressing HLA-DR/DQ heterodimers demonstrates that TM902 and TM903 mAbs are both specific for the DQ-beta chain. Comparison of the amino acid sequences of the DQ-beta chain suggests the involvement of residues 84-90 (QLELRTT) in the formation of TM902 epitope and of residues 54-55 (GR) in the formation of TM903 epitope.

Analysis of HLA specificity of human monoclonal antibodies by cytofluorimetry and cell ELISA

In this study we report on the characterization of cytotoxic human monoclonal antibodies (HmAb) detecting polymorphic HLA class II specificities using cytofluorimetric analysis in combination with micro cell ELISA. In both techniques, five anti-HLA HmAb were tested against HLA-transfected murine L cells as target cells and the bound antibody was detected, either by cytofluorimetry or by cell ELISA reader, after addition of fluoresceinated or peroxidase-conjugated anti-human IgG+IgM antibodies, respectively. The results demonstrate that HmAb directed against HLA-DR, -DQ and -DP molecules can be efficiently discriminated by cytofluorimetry and cell ELISA, which appear to be highly sensitive and perfectly comparable to the standard cytotoxicity assay.