title: Determinants of serum levels of surfactant proteins A and B and Clara cell protein CC16.
abstract: Increased leakage of surfactant proteins A and B (SP-A and SP-B) and Clara cell secretory protein (CC16) from the air spaces into the circulation occurs in a range of respiratory conditions. However, circulating levels depend not only on the rate of entry into the circulation, but also on the rate of clearance. In order to clarify the role of the kidney in the clearance of these proteins, serum levels were related to markers of glomerular filtration in 54 non-smoking patients with varying degrees of renal dysfunction, none of whom had respiratory disease or were receiving dialysis at the time of sampling. Serum SP-A was related to SP-B (r = 0.53, p < 0.001) and to CC16 (r = 0.33, p < 0.02). Similarly, SP-B was related to CC16 (r = 0.39, p < 0.004). Stepwise multiple linear regression analysis suggested that serum SP-A and SP-B are influenced by age (approximately 20 and approximately 25% of variance, respectively), whereas CC16 is determined by renal function and, to a lesser extent, by body weight (approximately 63% of variance in total). We conclude that CC16 is cleared from blood by the renal route, whereas SP-A and SP-B are not. Serum SP-A and SP-B are influenced by age, which we speculate reflects increased damage to the alveolocapillary barrier.
authors.affiliation: Industrial Toxicology and Occupational Medicine, Medical School, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: Cedric
authors.initials: C
authors.lastname: Hermans
authors.forename: Ping
authors.initials: P
authors.lastname: Dong
authors.forename: Marjorie
authors.initials: M
authors.lastname: Robin
authors.forename: Michel
authors.initials: M
authors.lastname: Jadoul
authors.forename: Alfred
authors.initials: A
authors.lastname: Bernard
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Bersten
authors.forename: Ian R
authors.initials: IR
authors.lastname: Doyle
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001835:Body Weight; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000097:blood; D008297:Male; D008875:Middle Aged; D010539:Permeability; D037662:Pulmonary Surfactant-Associated Protein A / Q000097:blood*; D037701:Pulmonary Surfactant-Associated Protein B / Q000097:blood*; D037661:Pulmonary Surfactant-Associated Proteins / Q000097:blood; D012128:Respiratory Distress Syndrome / Q000097:blood; D020545:Respiratory Mucosa / Q000473:pathology; D014598:Uteroglobin / Q000097:blood*
chemical_list: D037662:Pulmonary Surfactant-Associated Protein A; D037701:Pulmonary Surfactant-Associated Protein B; D037661:Pulmonary Surfactant-Associated Proteins; C556389:SCGB1A1 protein, human; D014598:Uteroglobin