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A common antigenic epitope expressed on human Pneumocystis carinii
T Amagai1, Y Matsumoto, Y Sakai
1Meiji College of Oriental Medicine, Prefectural University of Medicine, Kyoto, Japan.
Insights
Researchers identified a common antigen in Pneumocystis carinii (PcH) using monoclonal antibodies (MAb). This discovery may aid in diagnosing PcH infections and understanding its biology.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Antigenic heterogeneity in human Pneumocystis carinii (PcH) isolates has been recently observed.
- Monoclonal antibodies (MAb) were generated against PcH from both non-AIDS and AIDS patients.
Purpose of the Study:
- To characterize antigenic epitopes of human Pneumocystis carinii.
- To identify common antigens for diagnostic and research applications.
Main Methods:
- Production of monoclonal antibodies (MAb) against human Pneumocystis carinii (PcH).
- Detection of PcH antigen using indirect immunofluorescence and immunoblotting.
- Evaluation of MAb reactivity against various PcH isolates.
Main Results:
- Specific MAb (Group II) stained all PcH isolates, indicating conserved epitopes.
- Some MAb recognized both cyst and trophozoite stages of PcH.
- Immunoblotting identified a common 92 kDa antigen recognized by all tested MAb.
Conclusions:
- A common antigenic epitope on PcH has been identified.
- MAb recognizing this epitope show potential for PcH diagnosis.
- These MAb can be valuable tools for biological characterization studies of PcH.
Abstract:
Recently antigenic heterogeneity in human Pneumocystis carinii (Pc) isolates was observed in several laboratories. Monoclonal antibodies (MAb) were produced to human Pc (PcH) from a lung autopsy sample from a non-AIDS patient (MAb Group I, n = 10), or from bronchoalveolar lavage (BAL) fluid from AIDS patients (MAb Group II, n = 8). To detect Pc antigen from specimens, indirect immunofluorescence and immunoblotting techniques were used. The reactivity was evaluated by using one autopsy sample from the non-AIDS patient and 14 BAL samples from AIDS patients. The MAb in group I (C5-9, E9) stained a part of PcH from all isolates. On the other hand, several MAb in group II (L20-5, M34-2, M78-3, M79-5, N23-4) stained all PcH from all isolates. Some MAb (C5-9, E9, M34-2, M78-3) stained cysts as well as trophozoites. Immunoblot studies detected a 92 kDa molecule as a common antigen by all of these MAb. Therefore, we have found a common antigenic epitope on PcH and MAb that recognize this epitope may become useful for diagnosis of infection and for biological characterization studies on the organism.