Surfactant protein A and D expression in the porcine Eustachian tube.

Surfactant proteins A and D are collectins which are considered to play an important role in the innate immunity of lungs. Our aim was to investigate whether surfactant protein A or D is expressed in the porcine Eustachian tube originating from the upper airways. Both surfactant proteins A and D were present in the epithelial cells of the Eustachian tube, as shown by strong immunostaining. Using RT-PCR and Northern hybridization, these collectins were detected in the Eustachian tube. The present study is the first report demonstrating surfactant protein gene expression in the Eustachian tube. Surfactant proteins A and D may be important in the antibody-independent protection of the middle ear.