T-cell Subsets and Antifungal Host Defenses

Abstract

It has been long appreciated that protective immunity against fungal pathogens is dependent on activation of cellular adaptive immune responses represented by T lymphocytes. The T-helper (Th)1/Th2 paradigm has proven to be essential for the understanding of protective adaptive host responses. Studies that have examined the significance of regulatory T cells in fungal infection, and the recent discovery of a new T-helper subset called Th17 have provided crucial information for understanding the complementary roles played by the various T-helper lymphocytes in systemic versus mucosal antifungal host defense. This review provides an overview of the role of the various T-cell subsets during fungal infections and the reciprocal regulation between the T-cell subsets contributing to the tailored host response against fungal pathogens.

Fig. 1

The interplay between T-cell subsets during antifungal host defense. Antigen presenting cells (APCs) can polarize T helper (Th) responses by generating specific cytokine profiles. Th1 and Th17 cells play an important role in the recruitment and activation of neutrophils that are crucial for an adequate host defense against fungal pathogens. Th1 and Th17 can be inhibited by Th2 and/or T regulatory (Treg) subsets, which can be beneficial in the setting of an exaggerated immune response, but can be deleterious if a potent proinflammatory response is necessary. IFNγ—interferon-γ; IL—interleukin; PMN—polymorphonuclear cells