Elevated levels of interleukin-13 and IL-18 in patients with dengue hemorrhagic fever

Interleukin (IL)-13 is produced by T helper 2 (Th2)-type cells and inhibits the production of proinflammatory cytokines by activated monocytes, while IL-18 is a pleiotropic cytokine that induces interferon-gamma and plays an important role in the development of Th1-type cells. Role of the shift from a Th1-type response to Th2-type has been suggested in the pathogenesis of dengue hemorrhagic fever (DHF). This study was undertaken to investigate the possible protective/pathogenic role of IL-13 and IL-18 in patients with DHF. Sera were collected from a total of 84 patients with various grades of dengue illness and 21 normal healthy controls and tested for IL-13 and IL-18 levels using commercial enzyme-linked immunosorbent assay kits. The results showed that very low levels of IL-13 (4 +/- 3 pg ml(-1)) and IL-18 (15 +/- 3 pg ml(-1)) were detected in the sera of healthy controls. Ln dengue patients, the levels of IL-13 and IL-18 were the highest in the patients with DHF grade IV (205 +/- 103 pg ml(-1) and 366 +/- 155 pg ml(-1), respectively) and the lowest in patients with dengue fever (22 +/- 117 pg ml(-1) and 76 +/- 50 pg ml(-1), respectively). Both the cytokines appeared (IL-13 = 20 +/- 11 pg ml(-1) and IL-18 = 70 +/- 45 pg ml) during the first 4 days of illness and reached peak levels (IL-13 = 204 +/- 96 pg ml(-1) and IL-18 = 360 +/- 148 pg ml(-1)) by day 9 onwards. The presence of high levels of IL-13 and IL-18 during severe illness and late phases of the disease suggests that both of these cytokines may contribute to the shift from a Th1 to Th2-type response and thus to the pathogenesis of DHF. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.