Cryptococcus neoformans IV. The Not-So-Encapsulated Yeast.

Nonencapsulated cells of Cryptococcus neoformans which may have a diameter of less than 4 mum are capable of producing experimental cryptococcosis in mice. It has been established that this relatively small, nonencapsulated yeast can exist in soil. In this form, the organism could be more readily disseminated by air currents, and it is more likely to be inhaled into the lungs than the larger encapsulated yeast. Nonencapsulated cells produce sufficient capsular material to inhibit phagocytosis by 50% when incubated for 5 to 10 hr with human lung tissue in vitro. The general assumption that the encapsulated cells are the etiological agent of naturally acquired cryptococcosis may have to be revised.