Differential expression of cytotoxic molecules and killer cell inhibitory receptors in CD8+ and CD56+ cutaneous lymphomas

Cutaneous lymphomas of the cytotoxic phenotype, including CD8+ and CD56+ lymphomas, have only recently been recognized. To characterize the phenotypic profile of these lymphomas, we investigated the expression of both cytotoxic molecules and killer cell inhibitory receptors by immunohistochemistry techniques. Frozen sections from four CD8+ and from three CD56+ cutaneous lymphomas were stained for the cytotoxicity markers including T-cell restricted intracellular antigen-1, perforin, granzyme B, and for expression of the inhibitory receptors including p58.1, p58.2, p70, p140, CD94, NKG2, and leukocyte immunoglobulin-like receptor (LIR-1). Apart from LIR-1, the CD8+ lymphomas in our series express p70 and p140 from the inhibitory receptors and only one or two of the cytotoxic proteins. The CD56+ lymphomas, on the other hand, express only LIR-1 of the set of inhibitory receptors and the whole panel of cytotoxic antigens. Various subtypes of cytotoxic cutaneous lymphomas (CD8+ and CD56+) differ in regard to their phenotypic and functional profile, which may explain differences in their biological behavior.