Immunohistochemical expression of surfactant apoproteins in pneumonic ovine lungs


Abstract: The present study was undertaken to investigate the immunohistochemical expression of pulmonary surfactant proteins (SP-A, SP-B, proSP-C) associated with proliferating cell nuclear antigen (PCNA), thyroid transcription factor-I (TTF-I), and lymphocytic phenotypes (CD3+ T and CD79αcy+ B cells) in ovine lungs with exudative and verminous pneumonia. Pneumonic lungs (n = 50) were classified as presenting fibrinous bronchopneumonia (n = 16), abscessing necrotic bronchopneumonia (n = 10), verminous pneumonia (n = 15), and interstitial pneumonia (n = 9). The lungs with fibrinous bronchopneumonia displayed consolidation of lobes with adhesion to surrounding tissues. The lungs with verminous pneumonia were characterized by lungworm sections in airways. Type II pneumocytes were highly proliferated in the pneumonic lungs and revealed intense immune positivity for the surfactant proteins. Proliferated type II cells, lymphocytes, and fibroblasts showed a strong immune reaction for PCNA. TTF-I positivity occurred in the ovoid nuclei of alveolar II epithelial cells. Lymphoid infiltrations revealed a positive reaction to the CD markers. In conclusion, the present study revealed that alveolar type II epithelial cells were severely proliferated in the sheep lungs with pneumonia and produced most of surfactant proteins compared to normal type II cells. Consequently, type II cells are very important in the restoration of damaged lungs, and surfactant apoproteins might play an important role in the host defense mechanisms against involved microorganisms.

Keywords: Immunohistochemistry, pneumonic ovine lungs, surfactant proteins

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