Monoclonal antibodies (MT1, MT2, MB1, MB2, MB3) reactive with leukocyte subsets in paraffin-embedded tissue sections.

The absence of reactivity on routinely prepared tissue sections has hampered the use of monoclonal antileukocyte antibodies in diagnostic histopathology. Here we describe five new antibodies reactive with leukocyte subsets in formaldehyde-fixed, paraffin-embedded tissue sections. Antibody MT1 is reactive with mature and immature T cells and not with mature B cells. MT2 is reactive with mature T cells and B cells, but not with immature T cells, activated T cells, and germinal center B cells. Antibody MB1 is reactive with all B cells, with about 50% of mature T cells, and not with immature T cells. MB2 is reactive with all B cells and not with T cells. However, MB2 also stains endothelial cells and several types of epithelial cells. MB3 is reactive with B cells and histiocytes, but not with T cells. The antibodies were tested on a series of lymphomas that were also immunophenotyped with a panel of well-established reagents on frozen tissue sections. The results indicate that the MB and MT antibodies are useful tools in the study of reactive and neoplastic disorders of the lymphoid system.