A New Monoclonal Antibody Recognizing a Linear Determinant on the HLA-DRα Chain N-terminus

Abstract

We report the generation of a monoclonal antibody (MAb) that reacts to the N-terminus of the denatured HLA-DRα chain. The 1C4.6 MAb was raised against a peptide corresponding to amino acid residues 10 to 32 of a highly conserved region within the α1 domain of HLA-DR. This region partially overlaps with the epitope recognized by the conformationally dependent L243 MAb. In Western blot analysis, MAb 1C4.6 reacted with denatured HLA-DRα chains, but failed to bind the HLA-DRβ chain expressed individually by transfectant cells, confirming that it recognizes an epitope on the α-chain of HLA-DR. In addition, this antibody was found to be isotype specific to HLA-DRα, as it did not cross-react to HLA class II proteins HLA-DP and-HLA-DQ. The 1C4.6 MAb is a valuable addition to existing reagents used to probe the structure and function of MHC class II molecules. This anti-HLA-DRα1 domain MAb may prove valuable for studies of HLA class II heterodimer assembly, structure, and function, as well as for studies into the release of soluble MHC class II.