ABSTRACT
Pneumocystis carinii and related species survive as obligate or nearly obligate intraalveolar fungal parasites. Definitive evidence of continuous proliferation outside the confines of the lower respiratory tract has not yet been documented. Additional studies reveal that interactions of Pneumocystis with specific resident cells of the lung mediate important regulatory functions in the life cycle of this organism. In addition, host-cell recognition of the Pneumocystis surface is an important event in the initiation of inflammatory systems and host defense responses during the development of this pneumonia.
