title: Study of Clara cell 16, KL-6, and surfactant protein-D in serum as disease markers in pulmonary sarcoidosis.
abstract: OBJECTIVE
  To determine the discriminative value of serum Clara cell 16 (CC16), KL-6, and surfactant protein (SP)-D as markers of interstitial lung diseases, and their ability to reflect pulmonary disease severity and prognosis in sarcoidosis.
  
  
  METHODS
  Seventy-nine patients with sarcoidosis and 38 control subjects.
  
  
  METHODS
  Serum CC16, KL-6, and SP-D concentrations at disease presentation were measured. Pulmonary function tests and chest radiographs were analyzed at presentation and 2-year follow-up.
  
  
  RESULTS
  All markers co-correlated, and a significant difference was found between CC16, KL-6 (Krebs von den Lungen-6), and SP-D levels in patients with sarcoidosis and control subjects (p < 0.0001). Receiver operating characteristic curve analysis revealed largest area under the curve for KL-6. Significantly higher levels of CC16 and KL-6 were found in patients with parenchymal infiltration (stage II, III) compared to patients without parenchymal infiltration (stage I). In concordance, CC16 and KL-6 levels inversely correlated with diffusion capacity and total lung capacity, and KL-6 also with inspiratory vital capacity. Moreover, higher KL-6 levels were weakly but significantly associated with persistence or progression of parenchymal infiltrates at 2-year follow-up.
  
  
  CONCLUSIONS
  In this study, KL-6 appears to be the best discriminative marker in differentiating patients with sarcoidosis from healthy control subjects; however, as it is not a specific marker for this condition, this quality is unlikely to be useful as a diagnostic tool. Both CC16 and KL-6 may be of value in reflecting disease severity, and KL-6 tends to associate with pulmonary disease outcome.
authors.affiliation: Heart Lung Center Utrecht, Department of Pulmonology, St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, the Netherlands.
authors.forename: Rob
authors.initials: R
authors.lastname: Janssen
authors.forename: Hiroe
authors.initials: H
authors.lastname: Sato
authors.forename: Jan C
authors.initials: JC
authors.lastname: Grutters
authors.forename: Alfred
authors.initials: A
authors.lastname: Bernard
authors.forename: Heleen
authors.initials: H
authors.lastname: van Velzen-Blad
authors.forename: Roland M
authors.initials: RM
authors.lastname: du Bois
authors.forename: Jules M M
authors.initials: JM
authors.lastname: van den Bosch
mesh_terms: D000328:Adult; D000941:Antigens / Q000097:blood*; D000951:Antigens, Neoplasm; D015415:Biomarkers; D016022:Case-Control Studies; D004791:Enzyme Inhibitors / Q000097:blood*; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018396:Mucin-1; D009077:Mucins; D011506:Proteins / Q000378:metabolism*; D012372:ROC Curve; D011859:Radiography; D017565:Sarcoidosis, Pulmonary / Q000097:blood* / Q000145:classification / Q000000981:diagnostic imaging; D012720:Severity of Illness Index; D012907:Smoking / Q000009:adverse effects; D014598:Uteroglobin
chemical_list: D000941:Antigens; D000951:Antigens, Neoplasm; D015415:Biomarkers; D004791:Enzyme Inhibitors; D006023:Glycoproteins; C060192:MUC1 protein, human; D018396:Mucin-1; D009077:Mucins; D011506:Proteins; C556389:SCGB1A1 protein, human; D014598:Uteroglobin