RESUMEN
INTRODUCTION: Psoriasis is a disease with a strong immunological component in which there is a predominant T helper 1 cell-mediated immune response. Etanercept, a receptor for tumor necrosis factor a that blocks its action, is a new drug with proven efficacy in the treatment of psoriasis. OBJECTIVES: The primary objective of this study was to assess the histological response to etanercept by analyzing the lymphocyte populations in psoriatic plaques. The secondary objectives were to assess the clinical response to the drug using the Psoriasis Area and Severity Index (PASI) and to analyze the effect of etanercept on peripheral blood lymphocyte populations. METHODS: Ten patients with plaque psoriasis and a PASI score greater than 10 were included in the study. A clinical assessment was performed in all patients along with a 4-mm skin punch biopsy of a plaque and analysis of peripheral blood lymphocyte populations at baseline and after 12 weeks of etanercept therapy at a dose of 50 mg per week. RESULTS: There was a significant reduction in different lymphocyte populations in the plaques following treatment with etanercept. The mean (SD) number of CD4+ T lymphocytes per microscopic field decreased from 16.93 (8.13) at baseline to 6.51 (3.46) after treatment with etanercept (P < 007). CD8+ T lymphocytes also decreased from 17.73 (9.77) before treatment to 10.50 (9.4) after treatment (P < 005). An overall improvement in PASI score was also observed: 33.30 (10.71) at baseline versus 15.20 (13.28) following treatment (P < 008). Nine out of 10 patients showed improvement. No significant differences were observed in peripheral blood lymphocyte populations before and after treatment. CONCLUSIONS: Etanercept leads to clinical improvement of psoriasis and reduces inflammatory infiltration of the lesions without affecting peripheral blood lymphocyte populations.