Reactivity of monoclonal antibody BE 2 in different stages of mycosis fungoides and in benign dermal infiltrates.

The cutaneous infiltrate in mycosis fungoides (MF) is predominantly composed of T4-positive T-cells. Attempts to distinguish the early stages of this condition from benign inflammatory infiltrates using anti-T3, T4 and other T-cell-associated antibodies have hitherto been unsuccessful. Recently a monoclonal antibody BE 2 has been described as selectively reacting against leukemic cells in patients with cutaneous T-cell lymphoma. To investigate whether the BE 2 antigen is differentially expressed in different stages of MF and benign dermatoses, thus facilitating diagnosis, especially of early MF, the reactivity of monoclonal antibody BE 2 against cutaneous infiltrates from such conditions was assessed. In the early stages of MF only a small number of reactive cells was present. In benign inflammatory infiltrates, especially in those that clinically and histologically were hardly distinguishable from early MF, BE 2 reactivity was essentially the same as in eczematous-stage MF. Lesions from plaque and tumor stage MF contained large numbers of BE 2-reactive cells. Our results indicate that expression of BE 2 is associated with the stage of a given MF lesion and is essentially identical in early MF and eczematous lesions with a similar histopathological appearance.