CD8-positive tumor-infiltrating lymphocytes influence the long-term survival of patients with mycosis fungoides.

Abstract

Nonneoplastic mononuclear cells commonly infiltrate lesions of mycosis fungoides. We sought to determine the immunophenotypic characteristics of these cells and to determine whether the presence of CD8+ tumor-infiltrating lymphocytes has an impact on prognosis. Skin biopsy specimens from 78 patients were stained with immunopleroxidase techniques to determine their phenotypic characteristics. The proportion of CD8+ tumor-infiltrating lymphocytes was quantified and compared with stage of disease and survival rate. Patients with more limited T-stage disease tended to have a higher proportion of CD8+ cells in their skin biopsy specimens, compared with patients with more advanced T-stage disease. Within each T-stage patients with a larger proportion of CD8+ cells had a better survival rate than those with fewer CD8+ cells (p < 0.05 for T1 and T3). A multivariate analysis confirmed the importance of T stage (p = 0.0006), overall stage (p = 0.0112), and CD8 positivity (p = 0.0335) in this cohort of patients. CD8+ tumor-infiltrating lymphocytes in mycosis fungoides correlate with improved survival rate and may exert an antitumor effect rather than being mere bystander cells.