An assessment of the diagnostic value of the monoclonal antibodies Leu 8, OKT9, OKT10 and Ki67 in cutaneous lymphocytic infiltrates.

Biopsies from 63 patients, 40 with mycosis fungoides (MF) and 23 with other lymphocytic infiltrates, were stained with a panel of monoclonal antibodies to differentiation antigens (OKT10, Leu 8), to activation antigens (OKT9), and to an antigen expressed by all dividing cells (Ki67) to establish whether this panel was of value in the diagnosis of mycosis fungoides. None of these antibodies used in isolation was found to give a staining pattern specific for mycosis fungoides, but the phenotype Leu 3a+, OKT9+, Leu 8- of the majority of lymphocytes in the cutaneous infiltrate was strongly suggestive. The presence of Leu 3a+ Leu 8- lymphocytes is of particular interest in that in the peripheral blood both of normal subjects and of MF patients Leu 3a+ lymphocytes also are predominantly Leu 8+, were the lymphocytes in the cutaneous infiltrates of the non-MF infiltrates included in this study.