Immunity to Commensal Fungi: Detente and Disease

Fungi are ubiquitous in our environment, and a healthy immune systemis essential to maintain adequate protection from fungal infections. When this protection breaks down, superficial and invasive fungal infections cause diseases that range from irritating to life-threatening. Millions of people worldwide develop invasive infections during their lives, and mortality for these infections often exceeds 50%. Nevertheless, we are normally colonized with many of the same disease-causing fungi (e.g., on the skin or in the gut). Recent research is dramatically expanding our understanding of the mechanisms by which our immune systemsinteract with these organisms in health and disease. In this review, we discuss what is currently known about where and how the immune systeminteracts with common fungi.