Monoclonal antibody HML-1, a marker for intraepithelial T cells and lymphomas derived thereof, also recognizes hairy cell leukemia and some B-cell lymphomas.

Current views regard monoclonal antibody HML-1 as an exquisite marker for intraepithelial T cells and primary intestinal and cutaneous T-cell lymphomas. We show that HML-1 reacted with 11 of 12 cases of hairy cell leukemia, with 1 of 13 cases of primary gastrointestinal B-cell lymphoma, and with an unclassified large-cell B lymphoma of the thoracic wall. We conclude that HML-1 is not restricted to the T-cell lineage and that the HML-1 antigen is expressed in a small subset of both T- and B-cell neoplasms.