Immunosuppressive activity of leishmania major culture supernatant

BALB/c mice are highly susceptible to infection with the protozoan parasite Leishmania major. This susceptibility has been attributed in part to the expansion of Th2 cells and production of their cytokines, IL-4 and IL-10 and down-regulation of Th1 cytokine, INF-gamma. The inability of susceptible hosts to mount the immune response necessary to activate macrophage and destroy the parasites can be due to the parasite-specific proteins that are able to modulate the immune system. In this report, we monitored the culture supernatant of the parasite in order to show the existence of immunosuppressive factor. The L. major parasites were isolated from lesion of infected BALB/c mice. Amastigotes were grown at 35 °C and promastigotes at 22-25°C in the presence of 10% FCS. Culture supernatants were harvested after 72 h of incubation and used for lymphocyte proliferation assay using lymph node and spleen cells stimulated with mitogens. We have shown that the excretory materials of promastigotes and axenic amastigotes have a potent immunosuppressive activity. Culture supernatants can suppress the proliferation of mitogen-stimulated lymph node lymphocytes [74%] or spleen cells [90%] in a dose-dependent manner. This result may show that parasite by excretory materials can influence INF-gamma production by T cells and macrophage activation in order to survive within the macrophage and propagating inside the phagolysosome

Skin testing with stsndard leishmanin of Iran

Delayed-type hypersensitivity [DTH] reaction measured by skin testing is an important indicator for evaluation of cellular immune response in leishmaniasis. Skin testing in leishmaniasis, known as leishmanin or Montenegro test, is used normally for immunoepidemiological studies and for diagnosis. In cutaneous leishmaniasis [CL], the skin test is positive during the active phase of disease and remains reactive in almost 100% of recovered cases. The present paper describes the preparation and evaluation of the standard leishmanins produced from a well characterized strain of Leishmania major, and their applications in human CL, Different batches of leishmanin preparations were prepared in standard conditions and their reactivities were tested in different areas. Specificity of reagents was evaluated in healthy individuals in non endemic area of Tehran. Sensitivity and potency of antigens were evaluated in recovered cases from cutaneous leishmaniasis [CL] in endemic areas for both urban CL [north - west of Tehran] and rural CL [Isfahan area].The skin testing was carried out by intradermally injection of 0.1 ml of antigen or control regent into forearm of the individuals. Data obtained showed that specificity is 100% for all preparations. In recovered cases, different batches of leishmanin showed high sensitivity in different foci of leishmaniasis [> 93% in urban CL foci, and > 95.83% in rural CL foci]. Also different batches of leishmanin demonstrated a reliable potency in cured cases from urban CL, with mean diameter of indurations between 11.85 +/- 3.78mmand 14.21 + 5.0 mm. Moreover, strong potency was found in healed cases of rural CL with mean indurations between 15.18+ 3.93 mm and 18.04 + 5.22 mm. Finally, the reactivity of leishmanin was tested and proved stable after eight years study in recovered cases, This standard leishmanin, has also been tested in research centers of the country and abroad, and compared with other reagents, and selected by FDR as a reference reagent for vaccine trials