Iranian

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Partially purified antigenic fractions of Leishmania major promastigotes were obtained by sodium dodecyl sulfate (SDS-PAGE) and electro-elution. Three isolated protein fractions designated as frac‌tions (Fr.) 1, 2, and 3 correspond to 40-60, 60-80, 80-100 kilodalton (kDa) respectively. They were used for immunization of BALB/c mice against Leishmaniasis. The effects of these fractions on immune response of BALB/c mice against leishmanial infections was investigated by studying the infection course in infected mice, delayed type hypersensitivity (DTH) skin test, lymphocyte proliferation assay (LTT) in them. Subcutaneous immunization of mice with fraction 2 in conjugation with Complete Freund's Adjuvant (CFA) developed partial immunity against Leishmania major infection, and in‌duced specific DTH response. Meanwhile this fraction exhibited no exacerbating effect on leishmanial infection course. Subcutaneous immunization with fraction 1 also induced partial protection in lesser extent than fraction 2 against leishmanial infection.

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The early cytokines production in response to live logarithmic and stationary phase promastigotes of Leishmania major was examined on the peripheral blood cells of the healthy individuals. Whole blood cultures were stimulated by either logarithmic or stationary phase promastigotes. IFN- and IL-10 productions were assessed by specific sandwich ELISA. The results showed that the logarithmic promastigotes were more potent than the stationary promastigotes in induction of IFN-. In contrast, IL-10 production was significantly higher in the supernatants of the cells stimulated by the stationary promastigotes compared to the logarithmic phase of the parasites. The effect of BCG on IL-10 and IFN- productions induced by these two types of promastigotes was also studied. BCG had augmenting effect on the cytokine production. However, the difference between the logarithmic and the stationary promastigotes was still observed, since logarithmic parasites induced higher amount of IFN- and lower amount of IL-10 compared to the stationary parasites. In parallel, intracellular expression of IL-12 and IL-10 in the CD14+ cells was studied and the same results were obtained. The logarithmic phase parasites induced significantly higher expression of IL-12 and lower expression of IL-10 compared to the stationary phase parasites which induced lower expression of IL-12 and higher expression of IL-10. These results demonstrated that logarithmic promastigotes of L. major are more potent to induce Th1 response than stationary promastigotes which might have implication in vaccine preparation.