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.