Macrophage inflammatory protein 1alpha (MIP-1alpha)/CCL3 prevents the development of
eosinophilic pneumonia (EP) driven by a nonprotective T2-type immunity during
infection with a highly virulent strain of Cryptococcus neoformans. The present study evaluated the interaction of
MIP-1alpha with other innate immune system
cytokines by comparing the immune responses that followed pulmonary
infections with high- (C. neoformans 145A) and low (C. neoformans 52D)-virulence strains. In contrast to what was found for C. neoformans 145A
infection, lack of
MIP-1alpha in C. neoformans 52D
infection did not cause the development of EP. C. neoformans 52D induced
tumor necrosis factor alpha (
TNF-alpha),
gamma interferon (IFN-gamma), and MCP-1 in the lungs of infected wild-type (WT) and
MIP-1alpha knockout (KO) mice by day 7 postinfection. Both WT and
MIP-1alpha KO mice subsequently cleared this
infection. Thus, the robust expression of early inflammatory
cytokines in C. neoformans 52D-infected mice promoted the development of protective immunity even in the absence of
MIP-1alpha. Alternatively, C. neoformans 145A-infected WT and
MIP-1alpha KO mice had diminished
TNF-alpha, IFN-gamma, and macrophage
chemoattractant protein 1 (MCP-1) responses, indicating that virulent C. neoformans 145A evaded early innate host defenses. However C. neoformans 145A-infected WT mice had an early induction of
MIP-1alpha and subsequently did not develop EP. In contrast, C. neoformans 145A-infected
MIP-1alpha KO mice developed EP and had increased C. neoformans dissemination into the brain by day 35. We conclude that, in the absence of other innate immune response effector molecules,
MIP-1alpha is crucial to prevent the development of EP and to control C. neoformans dissemination to the brain.