CD8+T cells in cutaneous T-cell lymphoma: Expression of cytotoxic proteins, Fas ligand, and killing inhibitory receptors and their relationship with clinical behavior

Purpose : We investigated the number, phenotype, and prognostic significanc e of CD8+ T cells in patients with mycosis fungoides (MF) and CD30- primary cutaneous large T-cell lymphoma (PCLTCL). Patients and Method : Immunohistochemical stainings for CD8, granzyme B (Gr B), T cell-restricted intracellular antigen (TIA-1), Fas ligand (FasL), and killer-cell inhibitory receptors (KIRs; CD95, CD158a, and CD158b) were per formed on 83 first-diagnostic biopsy samples obtained from patients with pl aque-stage MF (n = 42), tumor-stage MF (n = 20), and CD30- PCLTCL (n = 21). Results: Serial sections and double-staining experiments showed that the la rge majority of CD8+ T cells in MF and CD30- PCLTCL expressed TIA-1 and Fas L, whereas only a minority expressed GrB, which suggested that these CD8+ T cells were partly activated cytotoxic T lymphocytes (CTLs). These CD8+ CTL s never or rarely expressed KIRs. This phenotype was a constant feature of CD8+ CTLs and did not alter with disease progression. In contrast, the medi an percentage of CD8+ CTLs in plaque-stage MF (22%), tumor-stage MF (7%), a nd CD30- PCLTCL (3%) differed significantly (P <.0001) and was associated w ith a significant decrease in 5-year survival. Also within the group of tum or-stage MF, a significant relation between CD8+ CTLs and survival was foun d. Multivariate analysis in the total group of MF demonstrated that both sk in stage and percentage of CD8+ CTLs were independent parameters of surviva l. Conclusion: Our results demonstrated that partly activated CD8+ CTLs were p resent in CTCL and that high proportions of these cells correlated with a b etter prognosis. This suggested that these CD8+ CTLs could play an importan t role in the antitumor response in these conditions. J Clin Oncol 19:4322- 4329. (C) 2001 by American Society of Clinical Oncology.