A mouse monoclonal antibody against a polymorphic determinant in a defined subset of DR molecules.

The hybridoma technique was used to produce a mouse monoclonal antibody, designated as XI 21.4, which belongs to the IgG2a class. It is active in complement-dependent cytotoxicity and detects a B-cell antigenic determinant associated with DR1, DR4, DRw10, and, possibly, DRw9. Microfingerprinting of the immunoprecipitate from a homozygous DR4 cell line shows a typical alpha DR pattern and a beta pattern coinciding with that of DR4 molecules.