Study on the role of interleukin-4 in experimental murine systemic candidiasis.

In order to investigate the role of interleukin-4 (IL-4) in experimental murine systemic Candidiasis, we created the intact and dexamethasone-induced immunosuppressed murine systemic Candidiasis models. In these models, two-site ELISA and RT-PCR were applied to determine the level of IL-4 protein and mRNA expression in spleens respectively, clone forming units (CFUs) of infected kidneys were determined with the plating dilution method, and mean survival time (MST) of the mice was recorded. The results showed that, when compared with the controls, protein level of IL-4 increased in both intact mice infected with lethal doses of yeast (day 3, P < 0.05; day 7, P < 0.001) and immunosuppressed mice infected with sublethal doses of yeast (day 3, P > 0.05; day 7, P < 0.05). Furthermore, the level of IL-4 was higher on day 7 than on day 3 after infection (P < 0.001 and P < 0.05 respectively in two groups). The tendency of IL-4 mRNA expression was similar with that of IL-4 protein. As for fungal loads in kidneys, CFUs were significantly higher on day 7 than on day 3 after infection (P < 0.001 in both groups). Mice in both groups succumbed to infection within several days. It was suggested that IL-4 might play a promoting role in the development of murine systemic Candidiasis.