Role of Cytokines in T Cell Immunity to a Pulmonary Cryptococcus neoformans Infection

The objective of these studies was to present an overview of our studies of the cytokine network and cellular interactions responsible for the T-cell-mediated inflammatory response in the lungs following infection by Cryptococcus neoformans. In a resistant strain of mice, moderately virulent cryptococci were progressively cleared from the lungs after week 1. Characterization of mitogen-induced cytokine production demonstrated that the T cells in the lungs during the first 3 weeks of infection resembled Th0 rather than Th1 cells. In addition, the production of IL-10 (by mitogen-stimulated leukocytes) could promote an increase in the ratio of Th2:Th1 cytokines in short-term in vitro cultures. In vivo, there were increases in the alveolar levels of tumor necrosis factor-alpha and IL-6 at weeks 1-3 and the chemokines monocyte chemoattractant protein-1 at weeks 1-2 followed by macrophage inflammatory protein-1 alpha and ENA-78 at week 3. Overall, the pulmonary inflammatory response to C. neoformans evolved over 5 weeks from granulocytic to mononuclear, suggesting a maturation to a Th1-type response by week 5.