Immunohistochemical analysis of human lymphomas with monoclonal antibodies to B cell and Ia antigens reactive in paraffin sections.

: Monoclonal antibodies (MoAbs) to B cell- and T cell-specific antigens uniformly have been restricted in their use to cell suspension or frozen section techniques because the antigens that they identify are either masked or lost in the fixation or paraffin-embedding processes. Antiimmunoglobulin antisera, although readily identifying cytoplasmic immunoglobulin in paraffin sections, has not been as useful as originally hoped since the majority of B cell lymphomas express surface immunoglobulins, which requires cell suspensions or frozen sections for detection. Because cell suspension procedures disrupt tissue architecture and frozen section techniques grossly distort morphology, neither method allows the combination of optimal morphologic and immunologic classification of lymphomas. We recently reported two MoAbs, LN-1 and LN-2, that react with B cells in paraffin sections. LN-1 reacts with the surface membrane and cytoplasm of germinal center B cells. LN-2 reacts uniquely with the nuclear membrane and cytoplasm of mantle zone and germinal center B cells and interdigitating histiocytes. We have also identified a new MoAb, LN-3, that reacts with the HLA-DR antigen in paraffin sections. We now report the use of LN-1, LN-2, and LN-3 in the analysis of paraffin sections from 58 non-Hodgkin's lymphomas and 15 cases of Hodgkin's disease. The types of cells reactive with these MoAbs in neoplastic lymphoid proliferations largely recapitulate their benign morphologic and immunologic counterparts. As a panel, LN-1, LN-2, and LN-3 were reactive with 98% of B cell lymphomas, and LN-1 and LN-2 were negative on all T cell lymphomas. In addition to identifying the cell of origin of these malignant proliferations, these MoAbs were also useful for identifying architectural features in neoplastic lymph nodes. Thus, these reagents provide the ability to assess the immunologic phenotype of neoplastic lymphocytes in conjunction with the critical morphologic criteria requiring paraffin embedding.