1Noha Nabil Doghaim, 2Raghda Zaki Talaat, 1Azza El-Toukhy 3Amani M. Abou El-Enein, 3Enayat Badr.
Departments of 1Dermatology, 2Microbiology and 3Clinical Pathology Faculty of Medicine. Tanta University
The spectrum of host responses to Mycobacterium leprae provides a model for investigating the role of cytokines in the pathogenesis of mycobacterial disease. To assess in situ cytokine patterns, messenger RNA extracted from leprosy skin biopsy specimens and peripheral blood mononuclear cells (PBMN) from 36 patients across the spectrum of the disease in addition to eight patients with leprosy reaction were amplified by the polymerase chain reaction with TNF-a, IL-2 and IL-10 specific primers. Of particular interest is tumor necrosis factor (TNF-a), a cytokine that may have both antimycobacterial and immunopathologic effects. To evaluate its potential role in leprosy, we noticed that mRNA coding for TNF-α in patients with the tuberculoid form of the disease were higher than in those with the lepromatous form, also its expression was extremely high in PBMN in cases of erythema nodosum leprosum (ENL), although relatively low levels were expressed in the skin lesions of these patients. At the site of mycobacterial infections, mRNA for Th1 as IL-2, predominated in tissue lesions with the resistant form of the disease, although T cells from the skin appeared to have reduced capacity to express IL-2 as compared with T cells from blood. The immunedeficiency state present in patients with lepromatous leprosy is explained partly by the impaired synthesis of IL-2 . In contrast , IL-10 mRNA expression was higher in MB than PB, while it was expressed in the PBMN of ENL but not detected in reversal reaction(RR) patients. Moreover, it was not detected in the skin lesions of either types of reactions. In conclusion, it appears that the dynamic immuno-pathologic states of the spectrum of leprosy are associated with different cytokine secretion by M. leprae response T cells.