Candidate counterparts of Sézary cells and adult T-cell lymphoma-leukaemia cells in normal peripheral blood: an ultrastructural study with the immunogold method and monoclonal antibodies.

The ultrastructural and immunologic features of normal convoluted T-lymphocytes were studied with a panel of monoclonal antibodies and the immunogold technique and these were compared with cells from patients with Sézary syndrome (SS) and adult T-cell lymphoma-leukaemia (ATLL). According to the characteristics of the nucleus, two distinct T-cell subtypes, representing 2-4% of normal peripheral blood lymphocytes were recognized: (i) a cerebriform lymphocyte ('Sézary-like') characterized by narrow and deep nuclear indentations, closely resembling the cells of SS, and (ii) a convoluted or polylobated lymphocyte ('ATLL-like'), with shorter and broader nuclear indentations than those seen in SS, that resemble the cells of ATLL. Both types of lymphocytes were positive with the monoclonal antibodies OKT3, OKT4, OKT17 and FMC3 and were negative with OKT8, OKM1 and FMC4 (anti-HLA-Dr) as SS and ATLL cells. A difference was observed with the expression of the anti-T monoclonal antibody 3Al: Sézary-like lymphocytes, like SS and ATLL cells, were 3Al negative whilst ATLL-like lymphocytes were 3Al positive. The close morphological and membrane phenotype similarities observed between these two types of lymphocytes and the cells from SS and ATLL suggest that they may well represent the normal counterparts of the malignant T cells in both conditions.