Cellular and humoral immune responses during intrathoracic paracoccidioidomycosis in BALB/c mice.

Paracoccidioidomycosis is a chronic infection that primarily affects the lungs. Here we investigated cellular and humoral immune responses after intrathoracic Paracoccidioidesbrasiliensis infection in BALB/c mice. P. brasiliensis-colony-forming units (CFUs), fungal DNA and granulomas in lungs increased progressively, peaking at day 90 postinfection (p.i.). IFN-gamma production was highest on day 15 p.i., declining thereafter. The kinetics of the NO production was similar to that described for IFN-gamma. In contrast, IL-10 increased from day 45 p.i. reaching a peak at day 90. Levels of serum IgG1 were higher than IgG2a between days 30 and 90 p.i. 30% of mice died by day 90 p.i. These data indicate that infection with P. brasiliensis by the intrathoracic route shows high IFN-gamma and NO production at day 15 p.i., unable to control multiplication of fungi, which appears to be associated with a progressive increase in IL-10 and in the number and complexity of granulomas.