Specific for rat MHC class II (RT-1B) antigen (monomorphic determinant on beta chain of RT-1B molecules). Does not cross-react with RT-1A, -C, -D rat MHC products. Can be used in immunofluorescence and flow cytometry, immunoblotting, immunoprecipitation, immunochemistry on frozen sections; for enumeration of B cells and monocytes; for localization of B cells/monocytes tissue sections; for affinity purification of RT-1B antigen of different haplotypes; for characterization of leukemia and lymphomas.