Abstract
Cryptococcus neoformans is a fungus that possesses two properties unique for yeast: (1) production of a polysaccharide capsule and (2) neurotropism. The natural route of infection by C. neoformans is the respiratory tract; thus, factors that regulate the development and recruitment of memory Th1 cells and monocytes into the brain are critical for an effective response against disseminated C. neoformans infection. Production of TNFα prior to day 7 is required to prevent colonization of the central nervous system (CNS). Th1 type immunity is required to clear established foci. In contrast, Th2 type immunity is ineffective at eliminating the infection in the brain and results in decreased survival. C. neoformans infection of MIP-1α and CCR5 knockout mice has highlighted the complex role that some chemokines may play in different organs. MIP-1α knockout mice have decreased leukocyte recruitment and cryptococcal clearance from the brain compared to wild-type mice. Thus, the host defence mechanisms that clear C. neoformans from the CNS appear to be similar to those in the lungs: via a Th1 cell-mediated inflammatory response that requires chemokines for the recruitment of effector cells.