Surfactant abnormalities in idiopathic pulmonary fibrosis, hypersensitivity pneumonitis and sarcoidosis

Bronchoalveolar lavage fluids (BALF) from patients,vith idiopathic pulmonar y fibrosis (IPF; n=36), hypersensitivity pneumonitis CHP; n=32) and sarcoid osis (n=44) were investigated for their surfactant properties and compared to healthy control subjects (n=29). The phospholipid (PL) and protein concentration, the PL:protein ratio, PL s ubclasses, and the surfactant apoproteins (SP)A and SP-B were quantified in BALF. Large surfactant aggregates (LSA) were measured by means of ultracen trifugation and assayed for surface activity using the pulsating bubble sur factometer. As compared to controls, SP-A concentrations, LSA content and PL:protein ra tios were significantly decreased in all groups, whereas PL and SP-B concen trations remained unchanged. Changes in the phospholipid profile, with redu ced percentages of phosphatidylcholine (not significant) and phosphatidylgl ycerol and increased fractions of phosphatidylinositol and sphingomyelin (p <0.05), occurred more in IPF than in KP, and not in sarcoidosis. Surface ac tivity was found to be severely impaired in IPF (minimum surface tension (g amma min) similar to 15-20 mN . m(-1)), but only modestly affected in HP an d sarcoidosis (gamma min similar to 5 mN . m(-1)) compared to controls (gam ma min similar to 0 mN . m(-1)). Reconstitution of pelleted surfactant mate rial with soluble BALF proteins further increased gamma min values. In conclusion, moderate changes in biochemical and physical surfactant prop erties are encountered in hypersensitivity pneumonitis and sarcoidosis, but pronounced disturbances occur in idiopathic pulmonary fibrosis.