interferon gamma unresponsiveness due to down-regulation of ifn-γr expression in experimental cutaneous leishmaniasis

it is now well documented that interferon gamma (ifn-γ) is the indispensable cytokine for inducing protective immunity against experimental and human cutaneous leishmaniaisis. the importance of ifn-γ receptor (ifn-γr) has also been studied. in the present study, we made attempts to find out whether l. major infection is able to alter the expression of ifn-γr in vivo. in addition, we studied the responsiveness to ifn-γ ex vivo. to do that, we assessed the expression of cd119 (ifn-γrα ) on cd45+ cells isolated from draining lymph nodes of infected and uninfected balb/c and c57bl/6 mice by flow cytometry. the mfi (mean fluorescence intensities) of cd119 on uninfected balb/c mice were 192.8 ± 18.4 but the cd119 mfi of infected balb/c mice were remarkably decreased (107.9±40.8). cd119 mfi of uninfected and infected c57bl/6 mice were 276.2 ± 17.1 and 140.4±43.0 respectively moreover, we measured the production of nitric oxide (no) by these cells in the presence of ifn-γ in order to study the function of ifn-γr. no production by draining lymph nodes cells of infected c57bl/6 mice in response to recombinant murine ifn-γ was significantly higher than the cells of infected balb/c mice (37.5 ± 0.6 and 11.6 ± 0.5 µm respectively, p<0.05). therefore, our results confirm the in vitro reports regarding the impairment of ifn-γ responsiveness due to leishmania infection.