Clinical significance of surfactant protein D as a serum marker for evaluating pulmonary fibrosis in patients with systemic sclerosis.
OBJECTIVE
To determine the clinical significance of surfactant protein D (SP-D), a useful marker for evaluating various lung diseases, in patients with systemic sclerosis (SSc) and to clarify any clinical significance between SP-D and KL-6, which is known to be correlated with pulmonary fibrosis (PF) in SSc patients.


METHODS
We used a specific enzyme-linked immunosorbent assay to measure serum SP-D levels in 83 patients with SSc and 31 healthy control subjects.


RESULTS
The serum levels of SP-D were significantly higher in patients with SSc than in healthy controls (mean +/- SD 81.9+/-59.2 versus 34.8+/-13.7 ng/ml). Serum SP-D levels in patients with diffuse cutaneous SSc were significantly higher than those in patients with limited cutaneous SSc (98.8+/-72.1 versus 66.8+/-40.0 ng/ml). Serum SP-D levels in patients with PF were significantly elevated compared with those in patients without PF (99.7+/-64.1 versus 65.3+/-49.4 ng/ml). Moreover, the incidences of decreased percentage diffusing capacity for carbon monoxide and decreased percentage vital capacity were also significantly greater in patients with elevated SP-D levels than in those with normal levels (67% versus 43% and 36% versus 17%, respectively). There was a significant positive correlation between serum levels of SP-D and KL-6. Serum SP-D and KL-6 levels showed almost the same sensitivities and specificities in the diagnosis of PF (68% versus 73% and 70% versus 74%, respectively). These two markers also predicted PF to almost the same degree (31% versus 33%, respectively).


CONCLUSIONS
These results suggest that SP-D, as well as KL-6, may be a useful serum marker for evaluating PF in patients with SSc.
Asano
Y
Y
University of Tokyo, Japan.
Ihn
H
H
Yamane
K
K
Yazawa
N
N
Kubo
M
M
Fujimoto
M
M
Tamaki
K
K
D000974:Antibodies, Antinuclear / Q000097:blood; D000941:Antigens; D000951:Antigens, Neoplasm; D015415:Biomarkers; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D022781:Hepatocytes; D006801:Humans; D008297:Male; D008875:Middle Aged; D018396:Mucin-1; D009077:Mucins; D011658:Pulmonary Fibrosis / Q000097:blood* / Q000209:etiology; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants / Q000097:blood*; D012594:Scleroderma, Localized / Q000097:blood* / Q000150:complications; D012595:Scleroderma, Systemic / Q000097:blood* / Q000150:complications; D012680:Sensitivity and Specificity
D000974:Antibodies, Antinuclear; D000941:Antigens; D000951:Antigens, Neoplasm; D015415:Biomarkers; D006023:Glycoproteins; C060192:MUC1 protein, human; D018396:Mucin-1; D009077:Mucins; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants