Olfactory mucosa response in guinea pigs following intranasal instillation with Cryptococcus neoformans. A histological and immunocytochemical study.

A central nervous system isolate from an acquired immunodeficiency syndrome (AIDS) patient of 10(3) Cryptococcus neoformans cells was instilled intranasally into guinea pigs. These were killed to evaluate the fate of the organisms and the response of the olfactory mucosa. Olfactory epithelium prevented the penetration of Cryptococcus neoformans and showed focal hyperplastic responses. The organisms, which manifested an affinity for the olfactory portion of the nasal cavities, were cleared from the olfactory space with no intervention from the immune system cells. By the end of the fifth week almost no organisms could be found and there was no histological evidence of dissemination. In contrast, destruction of the olfactory epithelium with zinc sulfate allowed the invasion of the subepithelial tissues, demonstrating the role of the olfactory mucosa in preventing infection with Cryptococcus neoformans through the nasal route. The results and the model described in this report may be useful in clarifying the pathogenic mechanisms of cryptococcosis and the non immune mediated host responses to Cryptococcus neoformans.