Immune response to Candida albicans

Abstract

Candida albicans causes infections of the skin, oral cavity and esophagus, gastrointestinal tract, vagina and vascular system. Most infections occur in immunocompromised hosts or debilitated patients. More than 90% of HIV positive patients suffer from mucosal candidiasis at least once in the course of this disease. The overall severity and chronicity of oral candidiasis in patients with AIDS are mainly attributed to the HIV-induced immune deficiency in the affected individuals, namely, the loss of T-helper cells and reduction in the number of CD4+ T lymphocytes. In mucosal colonization and systemic infections of mice by this fungus, Th1 cells mediate phagocyte-dependent protection, whose most important cytokines are IL-2, IFN-ã, TNF-á and IL-12. In contrast, production of inhibitory cytokines such as IL-4 and IL- 10 by Th2 cells are associated with disactivation of phagocytes and disease progression. Possibly, the growth of filamentous forms is better adapted to evade the cells of the immune system, whereas the yeast form may be the mode of proliferation in infected tissues. By the discriminative production of IL- 12 or IL-4 in response to the yeast or filamentous forms respectively, dendritic cells acquire the capacity of inducing the differentiation of CD4+ cells towards the Th1 or Th2 phenotypes.