A cytotoxic monoclonal antibody (HU-39) that detects DRw8 + DRw12.

A monoclonal antibody, HU-39, was produced by immunizing BALB/c mice with a cultured human B lymphoblastoid cell line, Shi-C3 (HLA-A24, A31, B51, Bw52, DR2, DRw12, DQw1, DQw3). Utilizing the complement-dependent cytotoxicity test, HU-39 was found to detect a polymorphic determinant common to HLA-DRw8 and HLA-DRw12, a split antigen of HLA-DR5. Although HU-39 reacted with the cells from all of nine DRw12 positive individuals, the cells from only 18 out of 21 DRw8 positive individuals reacted with HU-39 and the remaining three were negative for HU-39. The cytotoxicity of the antibody was reduced after the surface HLA-DR molecules of two cell lines, GI and EBV-Sh, typed as DRw8 and DRw12, respectively, were masked with F(ab')2, of anti-HLA-DR monoclonal antibody. The results of the sequential coprecipitation test and the two-dimensional gel electrophoresis by using EBV-Sh also indicated that HU-39 preferentially recognizes an epitope borne on the DR molecules, but not on the DQ molecules. Thus, HU-39 appeared to be of great value as a tissue typing reagent to define DRw8 and DRw12, the latter of which had been difficult to assign because of the lack of monospecific alloantisera.