Role of mast cells and cytokine profile [TNF-alpha, IFN-gmma, IL4 and IL-4 mRNA] in different types of leprosy

ABSTRACT

The aim of this study was to compare the number and the distribution of mast cells in biopsies taken in non reactional and reactional periods of the leprosy lesions. In addition, the expression of cytokines profile was analysed. 60 patients with leprosy were classified into three groups. Group I [non reactional leprosy included 38 patients, Group II [type I reaction] TIR included 13 patients, and Group III [type II reaction] TIJR included 9 patients. Cytokine profile was detected by determination of TNF-alpha, INF-gamma, IL-4 in the serum. In addition, IL-4 mRNA was determined in whole blood of all studied groups. Multiple punch biopsy specimens were taken from individual patients; for the examination of intra-lesional variation in mast cell numbers, specimens were taken from the centre of the lesion, the edge of tile lesion, and from the apparently unaffected skin outside the lesion at a point 2 cm from the nearest identifiable margin of the lesion. Comparison of INF-gamma and TNF-alpha in the sera of the different studied groups showed a significant difference between the groups, with a tendency to decrease in levels more in group III. Positive correlation between IFN-gamma and TNF-alpha, was detected. In addition, comparison of IL-4 and mRNA for IL-4 in the sera of the different studied groups showed a significant difference between the groups, with a tendency to increase in levels more in group III. Positive correlation between serum IL-4 and mRNA for IL-4, was observed. Density of mast cells in skin lesions of the different studied groups showed an insignificant difference between all groups as regards the centre of the lesion, while a significant difference was detected between group III and both groups I and II as regards mast cell density in the periphery and interstitium. The number of mast cells tends to increase from TT up to LL. A positive correlation was detected between mast cell density and IL-4 mRNA [r=0.57], while other studied cytokines did not show such a correlation. The cytokine profile is Th1 predominant in non reactional and TIR leprotic patients, while it shows Th2 predominance in TIIR leprotic patients. According to the pattern of cytokine production, mast cells are closely related to CD8+ T cells and IL-4mRNA leading to increased density of mast cells in skin lesions from TT up to LL, which in turn controls the out come of the disease