A monoclonal antibody recognizing HLA-DR2 on malignant and activated cells.

A monoclonal antibody, designated NDS15.38, which recognizes a polymorphic determinant of HLA-DR, was produced from a fusion in which mice were immunized with the human B lymphoblastoid cell line GIR2 (HLA type A1, B8, 27, Cw2, DR2,7). NDS15.38 functions efficiently as an affinity column and purifies a two-chain complex of molecular weight 33 000 and 30 000 under reducing conditions. The monoclonal antibody reacts with HLA-DR2-positive B lymphoblastoid cell lines and B lymphocytes from patients with chronic lymphatic leukemia in an indirect radioactive binding assay. However, NDS15.38 does not appear to react with peripheral blood B lymphocytes from normal individuals. Using a peroxidase staining technique, NDS15.38 was shown to react with phytohemagglutin (PHA)-stimulated lymphocytes and with apparently activated B cells in the germinal centers of lymph nodes from individuals who were tissue typed as HLA-DR2. Thus it appears that NDS15.38 recognizes a polymorphic determinant of HLA-DR on malignant and stimulated cells, but not on resting cells.