Detection of Pneumocystis carinii in lung-derived samples using monoclonal antibodies to an 82 kDa parasite component.

Monoclonal antibodies against Pneumocystis carinii (PC) antigenic epitopes resistant to denaturing procedures were developed by immunization of mice with isolated parasites and a urea extract of infected human lung tissue. Paraffin sections of infected lung tissue were used as antigen in the screening for reactive clones. The target antigen was identified as an 82 kDa parasite specific component in immunoblotting. The antibody showed no cross-reactivity with human lung tissue and various rat tissues and failed to react with a number of parasites and fungi. The antigenic epitope recognized by the anti-82 kDa component was resistant to denaturing procedures involved in fixation and processing of tissues for histology. The antibodies could be used for identification of both cysts and trophozoites in fixed smears of infected lung tissue and bronchoalveolar lavage fluid from infected individuals.