Co-expression of surfactant protein A and chicken lung lectin in chicken respiratory system

Chicken surfactant protein A (cSP-A) and chicken lung lectin (cLL) are C-type lectins that play important roles in pulmonary host defense responses. Herein, we explored the localization of cSP-A and cLL in the chicken respiratory system. Six tissues from 30-days-old SPF chickens were used to quantify the expression of cSP-A and cLL using the quantitative real-time reverse transcriptional polymerase chain reaction (qRT-PCR) and fluorescence multiplex immunohistochemistry staining (fluorescence mIHC staining). Results showed that cSP-A and cLL mRNA were highly expressed in lungs compared to other tissues. cSP-A mRNA expression levels in all tissues were higher compared with cLL expression levels as analyzed using qRT-PCR. Fluorescence mIHC co-expression of cSP-A and cLL were mainly detected in lung parabronchial epithelia, and mucosal epithelia of larynx, trachea, syrinx, bronchus and air sac, with cSP-A showing a stronger positive staining compared with cLL. cLL is expressed on both mucosal surfaces, some individual lung epithelial cells and cartilage cells, while cSP-A is mainly restricted to mucosal surfaces of the respiratory tract. These histological findings may be useful for understanding the biological significance of this pulmonary lectins in future studies.