GRANULOMATOUS REACTION IN THE HAMSTER-CHEEK POUCH INDUCED BY KILLED PARACOCCIDIOIDES-BRASILIENSIS

We have studied the role of Paracoccidioides brasiliensis viability in the morphology of paracoccidioidomycotic granulomas in the hamster ch eek pouch, an immunologically privileged site. Naive (N = 75) and prev iously sensitized (N = 50) two-month old male hamsters (Mesocricetus a uratus) were inoculated into the pouch with 5 x 10(5) live or heat- or formalin-killed fungi. Previously sensitized animals presented a posi tive footpad test and immunodiffusion demonstrable antibodies (titer 1 /32), at the time of sacrifice; naive animals were always negative for those immunological tests. The histological results showed that, like viable P. brasiliensis, killed fungi evoke typical epithelioid granul omas in 100% of animals, even in the absence of immunodiffusion or foo tpad test detectable immune response. The granulomas elicited by kille d fungi were devoid of giant cells or a mononuclear cell halo, suggest ing that live proliferating fungi or their products may be involved in these events.