Abstract
Pneumocystis carinii has two developmental stages: the trophozoite and the cyst. The differential specificity of monoclonal antibodies SMoAb (cysts only) and CMoAb (cysts and trophozoites) was used to analyse the trophozoite‐to‐cyst (T : C) ratio during recovery from P. carinii pneumonia (PCP) in a dexamethasone model in Wistar rats. In tissue homogenates the cysts decreased from week 0 to week 4 (4.10±1.57 106/g vs 0.069±0.021 106/g, pP. carinii is sensitive to the host response mounted during recovery, and support the theory that trophozoites probably also multiply in an extracystic asexual fission.