Fine structure and cytochemical study of the interaction between Fonsecaea pedrosoi and rat polymorphonuclear leukocyte.

The induction of a granulomatous reaction is frequently observed in subcutaneous mycoses. Our previous studies demonstrated that Fonsecaea pedrosoi was able to survive and proliferate in tissue macrophages and that activated macrophages were fungistatic but not fungicidal. By contrast, our present studies revealed that neutrophils were able to kill F. pedrosoi cells in periods shorter than 20 min. Several phases of the interaction process were analysed by light and electron microscopy. The kinetic analysis demonstrated no significant difference during the first hour of F. pedrosoi-neutrophil interaction. Electron microscopy images showed that neutrophils readily associated with and killed extracellular fungi; however, few fungi were ingested. During this process the activation of respiratory burst took place as evaluated by light and electron microscopy. Cytochemical activity of acid and alkaline phosphatase was detected in low levels during the host cell parasite interaction.