Granulomatous reaction in the hamster cheek pouch induced by killed Paracoccidioides brasiliensis

ABSTRACT

We have studied the role of Paracoccidioides brasiliensis viability in the morphology of paracoccidioidomycotic granulomas in the hamster cheek pouch, an immunologically privileged site. Naive (N=75) and previous senstized (N=50) two-month old male hamsters (Mesocricetus aurathus) were inoculated into the pouch with 5 x 10**5 live or heat-or formalim-killed fungi. Previously sensitized animals presented a positive foot pad tst and immunodiffusion demonstrable antibodies (titer 1/32), at the time of sacrifice, naive animals were always negative for those immunological tests. The histological resultas showed that, like viable P. brasilensis, killed fungi evoke typical epithelioid granulomas in 100 per cent of animal, even in the absence of immunodiffusion or footpad test detectable immune response. The granulomas elicited by killed fungi were devoid of giant cells or a mononuclear cell halo, suggfesting that live proliferating fungi or their products may be involved in these events