Dysregulation of IL-4 expression in lepromatous leprosy patients with and without erythema nodosum leprosum

In order to increase our understanding of the immunological basis of erythe ma nodosum leprosum (ENL), we studied Th-like cytokine profiles in 130 lepr osy patients, employing both the conventional and a novel, real-time, fluor ogenic reverse transcriptase-based PCR (RT-PCR). The concomitant expression of both Th-like cytokines, interferon-gamma and IL-4, and the regulatory c ytokines, IL-10 and IL-12, was studied in the peripheral blood cells of lep rosy patients with and without ENL. In the conventional RT-PCR, varied cyto kine profiles were observed in individual patients of all clinical types. F ifty-three percent of lepromatous patients without ENL and 59% of tuberculo id leprosy patients showed co-expression of IFN gamma and n-4, indicating a non-polarized Th 0 pattern. Of the 36 patients with ENL, 588 demonstrated a polarized Th 1 pattern, with only 30% expressing both cytokines. Semiquan titative RT-PCR indicated a lower expression of IL-4 compared to that of IF N gamma in the lepromatous patients without ENL; the difference was even gr eater among those with ENL. The sensitive, real-time PCR confirmed the down -regulation of IL-4 and IL-10, with absence of IL-4 in half of the patients , resulting in skewing of the cytokine response toward a Th I-like profile.