The effect of candidemia on immunologic parameters in breast tumor bearing patients is not well studied. Here, we hypothesised that candidemia in the tumor background may change the outcome of immunologic parameters and tumor condition.

Mice were divided into four groups, including normal, tumor, Candida infected (only Candidiasis) and tumor/Candidiasis groups. Tumor changes were recorded daily after tumor transplantation and induction of candidemia. Splenocytes of mice were harvested, cultured, and stimulated with PHA; afterwards, IL-4, IL-10, IFN-γ, TNF-α and TGF-β cytokines were assessed using ELISA kits. We also evaluated the population of CD4⁺CD25⁺Foxp3⁺ regulatory T cells in the tumor infiltrated and splenocytes.

The results showed that infection with C. albicans decreased the IFN-γ/IL-4 ratio in tumor/candidiasis and candidiasis groups versus their non-infected controls. IL-10, TGF-β and TNF-α levels increased in the candidiasis group. In addition, Candidemia led to an increase in the Treg population in tumor microenvironment and splenocytes of experimental groups compared with non-infected controls. Finally, candidemia increased tumor growth of tumor/Candidiasis group compared with the tumor group.

It seems that systemic infection with C. albicans could not only induce regulatory T cells but also result in dysregulation of cytokine network and thereby facilitate tumor growth.