A human monoclonal hybridoma antibody (TrJ1) specific for HLA-DQ2.

TrJ1 is a cytotoxic human hybridoma mAb (IgM lambda). Its reaction pattern with a panel of 42 HLA-defined lymphoblastoid B-cell lines correlated precisely with expression of DQ2. By flow cytometry it was shown that the binding of TrJ1 to DQ2 was efficiently blocked by the murine anti-DQ2 mAb 358.4, indicating that the TrJ1 and 358.4 epitopes overlap. TrJ1 reacted much better with EBV-transformed B cells than with B cells freshly isolated from blood. TrJ1 seemed suitable for typing freshly isolated B cells provided the incubation with complement lasted for 115 min in Terasaki plates. One or more of the DQ2-specific polymorphic amino acids E46, F47, L52, L55, K71 or A74, situated on the alpha-helix of the DQ2 beta chain, are probably critical for the TrJ1 epitope.