Abstract: Objective To investigate the effect of recombinant interleukin-18 (rlL-18) on systemic Candida albicans infection in mice.Methods A cyclophosphamide-induced immunosuppressed mouse model of systemic Candida albicans infection was established.The mice were divided into two groups,the treatment group injected with rIL-18 before infection with C.albicans,and the control group infected with C.albicans but not given rIL-18 injection.Both groups included 15 mice,and 5 mice were killed for examination respectively at 2,3 and 7 days after the infection.Colony forming units (cfu) of C.albicans were counted in the kidney and spleen with plating dilution method.The histopathological changes and degree of infection were graded in the kidney and spleen.The levels of interferon gamma (IFN-γ) was measured in the spleen by enzyme-linked immunosorbent assay (ELISA).Results The number of cfu in the kidney was significantly lower in the treatment group than in the control group at 2,3 and 7 days after the infection (4.996±0.063 vs 5.786±0.110,4.765±0.188 vs 6.097±0.079,3.984±0.133 vs 5.996±0.082,all P<0.01).Compared with the control group,the scores of histopathological changes in the kidney were lower, and the degree of infection was milder in the treatment group (both P<0.05).After infection,both the cfu number and score of histopathological changes were lower in the spleen of treatment group than in that of control group,but no statistical difference was observed for the difference (both P>0.05).The IFN-γlevels in the spleen were significantly higher in the treatment group than in the control group at the three time points (73.5292±6.0701 pg/mL vs 40.5109±4.4556 pg/mL,92.1807±7.8196 pg/mL vs 59.4145±5.0410 pg/mL,108.5638±9.8024 pg/mL vs 108.5638±9.8024 pg/mL,all P<0.01).Conclusion It is demonstrated that rIL-18 has a protective effect against systemic Candida albicans infection in mice.

Key words: Candidiasis, Interleukin-18, Animal testing alternatives