HETEROGENEITY OF CD3 ANTIGEN EXPRESSION IN T-CELL LYMPHOMA

CD3 antigen expression was studied in a series of 98 T-cell lymphomas, using polyclonal antibodies which recognize this molecule in routinel y processed, paraffin-embedded, tissue. We identified 40 cases in whic h CD3 was present on only a proportion of the neoplastic cells. This p henomenon of heterogeneous CD3 expression was commonest in pleomorphic T-cell lymphomas (22/42 cases) and in CD30 (Ki-1)-positive lymphomas (5/11 cases), and was less frequently observed in mycosis fungoides (4 /18 cases) and not seen in T-cell lymphoblastic lymphoma (0/9 cases). CD3 expression was often related to cell morphology, with CD3 antigen being present on the smaller neoplastic cells but absent from the larg er ones. The diagnostic significance of these observations is that, on occasion. it may be possible to diagnose a lymphoma as being of T-cel l origin in paraffin sections by demonstrating a minor subpopulation o f CD3-positive neoplastic cells.