en خالص‌سازی فاکتور ایمونوساپرسیو ترشح شده از انگل لیشمانیا ماژور مقاله کامل Full Length/Original Article <font face="times new roman,times,serif">Recent scientific evidence indicates that distinct patterns of susceptibility in BALB/c mice to Leishmania major infection are attributable to the differential expansion of distinct CD4+ T-cell subsets and their cytokines production. Production of the Th1 cytokine IFN-g is associated with resistance, whereas production of the Th2 cytokines IL-4 and IL-10 are associated with extreme susceptibility. The major host immune defense mechanism against Leishmania is activation of macrophages by INF-&gamma; derived from T cells. The inability of susceptible hosts to mount the immune response necessary to activate macrophage and destroy the parasites may be due to the parasite-specific proteins that are able to suppress the immune system. In the present study, we have semi-purified the excreted antigens of Leishmania major promastigote and amastigote by column chromatography. The isolated fraction showed a potent immunosuppressive activity on normal BALB/c mice lymphocytes stimulated with mitogens. Fifteen microgram of the isolated fraction caused 81% suppression of lymphocyte proliferation. These data may suggest that the parasite by secreting immunosuppressive factor down regulate the immune system and as a result survive in the body </font> Leishmania major, Amastigote, Promastigote, Immunosuppressive Factor, Purification 95 99 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-252&slc_lang=en&sid=1 Mohsen Abolhassani محسن ابوالحسنی mabolhassani@yahoo.com Yes Haideh Darabi هایده دارابی No