Analysis of the major surfactant-associated proteins in human lung.

The protein component of human pulmonary surfactant was analysed. A purified surfactant preparation, after delipidation, was subjected to gel filtration on Sephadex G-200. The proteins present in the surfactant were categorised by means of SDS-polyacrylamide gel electrophoresis into serum and non-serum components. Molecular masses determination showed the presence of three sub-groups with molecular masses of 60-68 kDa, 28-36 kDa and 10-18 kDa, respectively. Antiserum generated against 28-36 kDa protein strongly reacted with the purified surfactant and amniotic fluid, while it did not show any cross reactivity with other groups of proteins and serum in a double diffusion immunoprecipitation assay. We propose that this protein is the major non-serum surfactant-associated protein present in human lung surfactant.