Pneumocystis antigen appearance during immunosuppression

The sequential appearance of Pneumocystis carinii (Pc) antigens during the progression of immunosuppression in rats was studied using the immunoblotting technique and specific immunologic probes. Putative Pc soluble antigens, with molecular weights of approximately 70 and 90 kd, were detected as early as 2 wk after initiation of immunosuppression in rats using a pool of monoclonal antibodies produced to Pc isolated from lungs using enzymatic digestion. Monoclonal antibodies produced to Pc isolated by massaging the lung tissue using a Stomacher apparatus and infection-derived sera did not detect soluble antigens until at least the 6th wk of immunosuppression. Analysis of Pc pellets obtained from Stomacher- and lavage-processed lungs revealed that the lower molecular weight antigens (less than or equal to 40, 45 and possibly 55-60 kd) were recognized early during the immunosuppression process.