شكل گيري بيان mRNA سايتوكاين هاي Th1 و Th2 در گره هاي لنفي موش هاي BALB/c آلوده به ليشمانيا ماژور

Development of Thl and Th2 cytokines mRNA expression in lymph node of BALB/c mice infected with Leishmania major

Leishmania major is a protozoan parasite and the causative agent of the cutaneous leishmaniasis. Anti-leishmanial immune response is shown to depend upon the genotype of the host. Hence some inbred strains of mice are susceptible while others are resistant to Leishmania major. The resistance is developed by T-helper type-1 (Thl) cells by producing IFN-y and IL-12, while the susceptibility is mediated by Th2 cells producing IL-4, IL-5 and IL-10. It has been shown that IFN-y activates macrophages to kill the intracellular amastigotes. In contrast, Th2 immune response limits the action of Thl functions via IL-10 and IL-4, which results in deactivation of macrophages and growth of intracellular parasite and subsequent exacerbation of disease progression. The aim of this research was to detect how and when the cytokines mRNA of Thl and Th2 are induced in BALB/c mice inoculated by standard strain of L. major. In this study, strain of L. major was inoculated to BALB/c mice and their lymph nodes (LN) were separated in different periods of time (3 hr, 16 hr, 40 hr and first, third and fifth weeks). Total RNA of LN was extracted using molecular procedures and cDNA was made by reverse transcriptase. Expression of IFN- y, IL-2, IL-4, IL-10 and IL-12 mRNA was studied by designing specific primers, using Real Time PCR. Data obtained are expressed as the fold increase in mRNA expression of cytokines induced by L. major parasites in BALB/c mice. Results obtained showed that mRNA of the major cytokines of Thl, including IFN-y and IL-12 is not expressed in high level in LN in early and late period of post-infection (except 40 hr post-infection). While, mRNA of IL-4, the important cytokine of Th2 response is expressed in high level from 3 h post-infection and raises to peak at 40 h and continues in late period post-infection, which results in initiation of Th2 response.