Monoclonal antibody patterns in lymphomatoid papulosis.

Atypical cells resembling Reed-Sternberg cells are a characteristic histologic feature of lymphomatoid papulosis. Thus far no consistent data are available on the nature of these cells, or a possible antigenic relationship between them and Reed-Sternberg cells. Twenty-four biopsy specimens from 14 patients with lymphomatoid papulosis were immunolabeled with antibodies against Ki-1 and other Reed-Sternberg cell-associated antigens. In all cases a proportion of the large, atypical cells expressed the Ki-1 antigen. In contrast, in 20 biopsy specimens of benign inflammatory skin lesions or mycosis fungoides, Ki-1-positive cells were absent or only occasionally present. Furthermore, the large atypical cells of lymphomatoid papulosis also expressed other antigens (for example, T3, T4, HLA-DR, IL-2 receptors) that have previously been demonstrated on Reed-Sternberg cells. Our findings, together with the observation that the Ki-1 antigen can be induced on peripheral blood lymphocytes after prolonged phytohemagglutinin stimulation, suggest that the Ki-1-positive cells in lymphomatoid papulosis are activated T cells closely related to the Reed-Sternberg cells of Hodgkin's disease.