Comparative study of serum surfactant protein-D and KL-6 concentrations in patients with systemic sclerosis as markers for monitoring the activity of pulmonary fibrosis.
OBJECTIVE
To clarify the clinical significance of surfactant protein-D (SP-D) and KL-6 in the diagnosis and monitoring of pulmonary fibrosis (PF) in patients with systemic sclerosis (SSc), and to evaluate the differences between SP-D and KL-6.


METHODS
Serum SP-D and KL-6 concentrations were determined by ELISA in 42 SSc patients. In a retrospective longitudinal study, 83 serum samples from 6 SSc patients were analyzed during a followup period of 0.6-6.3 years.


RESULTS
SP-D and KL-6 concentrations at the first visit were higher in patients with SSc, especially those with PF, compared with healthy controls. Increased concentrations of SP-D were associated with decreased DLCO and decreased vital capacity in SSc patients more strongly than those of KL-6. The sensitivity and specificity for PF were 91% and 88% for SP-D and 39% and 100% for KL-6, respectively. In the longitudinal study, both SP-D and KL-6 concentrations were associated with activity of PF in patients with SSc. SP-D concentrations changed more rapidly than KL-6 concentrations, in parallel with the PF activity.


CONCLUSIONS
SP-D was a more sensitive marker for PF than KL-6. By contrast, KL-6 showed higher specificity than SP-D. Combined use of these 2 serum markers would be more helpful to diagnose and monitor the PF activity in patients with SSc than single use of each marker.
Yanaba
Koichi
K
Department of Dermatology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
Hasegawa
Minoru
M
Takehara
Kazuhiko
K
Sato
Shinichi
S
D000328:Adult; D000941:Antigens / Q000097:blood*; D000951:Antigens, Neoplasm; D015415:Biomarkers; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D018396:Mucin-1; D009077:Mucins; D011658:Pulmonary Fibrosis / Q000097:blood* / Q000175:diagnosis*; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood*; D012595:Scleroderma, Systemic / Q000097:blood* / Q000175:diagnosis*; D012720:Severity of Illness Index
D000941:Antigens; D000951:Antigens, Neoplasm; D015415:Biomarkers; D006023:Glycoproteins; C060192:MUC1 protein, human; D018396:Mucin-1; D009077:Mucins; D037663:Pulmonary Surfactant-Associated Protein D