Serum neopterin as a marker for reactional states in leprosy

Reactions, a relatively common phenomenon among leprosy patients in treatme nt, require early detection and proper management to prevent serious sequel ae. It is generally accepted that reactional states are immunologically med iated and, as such, usually improve with immunomodulatory treatments such a s corticosteroids or thalidomide. Neopterin, a product of gamma-interferon- activated macrophages, is a marker for cell-mediated immune activation and may be useful to detect reactional states in leprosy. Here, we compared neo pterin levels in single serum samples From leprosy patients with and withou t reaction with untreated controls and, when available. serial samples amon g patients with and without reaction. Levels in the single sample measureme nts, conducted in 22 patients with a reversal reaction (mean 14.5 nmol l(-1 ), S.D. 8.7) and 13 with erythema nodosum leprosum (mean 16.9 nmol l(-1), S .D. 13.6), were significantly higher (P = 0.02 and P = 0.001, respectively) than levels in 26 untreated patients (mean 9.1 nmol l(-1), S.D. 7.3), Valu es above the upper limit of normal (10 nmol l(-1)) were found in seven of 2 6 untreated patients, 14 of the 22 reversal reaction patients (P = 0.01) an d 10 of the 13 ENL patients (P = 0.003). Serial serum samples, obtained fro m six patients that developed reactions and 14 that remained free of reacti on, indicated that reversal reaction or erythema nodosum leprosum parallele d a concomitant increase in the serum neopterin level. Neopterin levels gen erally declined upon corticosteroid therapy. Neopterin may be a useful mark er for reactional states in leprosy by providing a laboratory parameter to assess the onset, progression, response to therapy and resolution. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Sc ience B.V. All rights reserved.