Immune response and its clinical significance in fungal infection

Cryptococcus neoformans is an opportunistic fungal pathogen which causes fatal meningoencephalitis in patients with compromised immune responses. Host defense to this infection is mediated by cellular immunity. Th1-related cytokines including IFN-gamma, TNF-alpha, IL-12 and IL-18, play a critical role in host protection. When this fungal pathogen infects, activation of innate immunity is initiated by its recognition via pattern recognition receptors, in which sensing of cryptococcal DNA by TLR9 is involved. This process is followed by activation of innate immune lymphocytes, such as NKT and gammadeltaT cells. Thus, host defense to cryptococcal infection is strictly regulated by immune responses, and clarification of these responses is important for better understanding of the pathogenic mechanism of fungal infection.