Thymulin reduces the hyperalgesia and cytokine upregulation induced by cutaneous leishmaniasis in mice.

Cutaneous leishmaniasis (CL) in mice has been shown to produce hyperalgesia and upregulation of interleukin (IL)-1beta and nerve growth factor (NGF) levels. The aim of this study was to investigate the effects of thymulin on CL-induced hyperalgesia and cytokine upregulation. Daily treatment with thymulin (1, 100, and 1000 ng/ip) produced dose-dependent decreases in CL-induced hyperalgesia as assessed by the tail flick and the hot plate tests. The levels of NGF and IL-1beta were determined in the skin tissues of the hind leg in different groups (n = 5 each) of mice over a period of 5 weeks. Mice with CL showed sustained increase in the levels of IL-1beta and NGF which were reversed by thymulin (1 microg). Injection of thymulin only did not alter the nociceptive thresholds or the levels of IL-1beta and NGF. We conclude that thymulin can modulate the hyperalgesia induced by CL by decreasing the levels of the proinflammatory factors IL-1beta and NGF.