[Effects of surfactant TA on adherence and structure of human peripheral blood neutrophils]

Artificial surfactant is used to treat patients with the adult respiratory distress syndrome; we studied its effects on neutrophil function. Neutrophils were isolated from healthy volunteers and their adherence to plastic surfaces was used as an index of their function. Surfactant TA (S-TA, 0.16-5 mg/mL) dose-dependently inhibited neutrophil adherence stimulated by n-formyl-methionyl-leucyl-phenyl-alanine, phorbol myristate acetate, and tumor necrosis factor. This inhibition was observed whether untreated S-TA or heated S-TA was used. Electron microscopy revealed an increase in the number of apoptotic neutrophils with pyknotic nuclei and smooth cell surfaces after treatment with S-TA which suggests that neutrophils apoptosis was increased. The number of apoptotic neutrophils increased with increasing time of incubation with S-TA, and was also high in the presence of G-CSF, which inhibits neutrophil apoptosis. These results show that S-TA can inhibit neutrophil function, and they suggest that S-TA therapy for the adult respiratory distress syndrome not only corrects the surface-tension abnormality, but can also inhibit infiltration of neutrophils.