mAb KUL/05 identifies a denaturation-resistant determinant shared by class II MHC products DR, DQ and DP.

mAb KUL/05, a novel murine monoclonal antibody, reacts with molecules displaying the typical tissue distribution and molecular profile of class II MHC antigens. An extensive scrutiny employing serological and immunochemical assays on DR homozygous and DR alpha- mutant cell lines has shown that this reagent displays some additional, interesting features, namely mAb KUL/05 (a) binds in a broadly monomorphic fashion to cells of DR1 through seven specificities, (b) recognizes a determinant shared by a large proportion of DR, DQ and DP beta chains from most haplotypes, in both their monomeric and alpha chain-associated forms, and (c) reacts with frozen, acetone-fixed, as well as conventional, formalin-fixed, paraffin embedded tissues. Thus, mAb KUL/05 is likely to represent a useful adjunct for the study of the expression of class II MHC products in normal and pathological tissue specimens.