Expression of a T-cell antigen (Leu-1) by B-cell lymphomas.

The Leu-1 antigen has been defined by monoclonal antibodies (L17F12, T101, and OKT-1) as a pan-T-cell antigen present on all human peripheral blood T cells and thymocytes. Although originally thought to be confined to T-cell lineage, some cases of B-cell chronic lymphocytic leukemia have been found to react with these antibodies. Using a frozen section immunoperoxidase staining technique, 125 lymphomas with B-cell differentiation were examined for the presence of Leu-1 antigen. Leu-1 antigen was detected in 4 of 11 cases of diffuse small lymphocytic lymphoma (Rappaport's DWDL) and 3 of 4 cases of diffuse intermediate lymphocytic lymphoma. Follicular lymphomas less often expressed this antigen--2 of 29 cases of the small cleaved cell type (Rappaport's NPDL), none of 13 cases of mixed small cleaved and large cell type (Rappaport's NM), and 1 of 6 cases of large cell type (Rappaport's NH). Diffuse lymphomas of presumed follicular center cell origin expressed this antigen infrequently as well--1 of 3 cases of the small cleaved cell type (Rappaport's DPDL), neither of 2 cases of mixed small cleaved and large cell type (Rappaport's DM), and 3 of 43 of large cell type (cleaved/noncleaved) (Rappaport's DH). Diffuse large cell, immunoblastic lymphoma of B-cell type expressed Leu-1 in 1 of 6 cases. None of the 3 cases of Burkitt's lymphoma or of the three small noncleaved non-Burkitt's lymphoma (Rappaport's undifferentiated) expressed detectable Leu-1. B-lymphoblastic lymphoma (1 case) and B-cell unclassified lymphoma (1 case) both failed to express detectable Leu-1. It appears that this pan-T-cell antigen is mainly found on those B-cell lymphomas composed predominantly of small lymphocytes. This finding may be of use in distinguishing extranodal neoplastic collections of small lymphocytes from lymphocytic hyperplasias.