Study objectives: Serum KL-6 (Krebs von den Lungen-6)
has been recognized to be a marker for the activity of diffuse
interstitial lung diseases. The purpose of the study is to evaluate
serum KL-6 measurement as a marker for farmer’s lung disease
Design: A cross-sectional survey of a cohort of
dairy farmers. Retrospective measurement of KL-6 stored serum samples
from those dairy farmers previously screened for FLD.
Setting: University hospital screening project for FLD
within a dairy-farming community in Japan.
Participants: Four hundred seventy-two dairy farmers were
invited to attend a local clinic.
results: We examined serum KL-6 concentrations in 272 farmers.
Subjects were classified into three groups: (1) 5 farmers with FLD, (2)
30 farmers with positive serum precipitating antibodies to
Saccharopolyspora rectivirgula and/or
Thermoactinomyces vulgaris without FLD
(Ab+), and (3) 237 farmers without these antibodies
(Ab−). Serum KL-6 concentrations in the FLD group were
significantly higher than those in the Ab+ and the
Ab− groups (1,263 ± 288 [SEM], 328 ± 57, and
207 ± 6 U/mL, respectively, p < 0.001). Serum KL-6 concentrations
in those with FLD were significantly higher than KL-6 concentrations
from stored screening samples from the same individual when FLD was not
diagnosed (1,263 ± 288 and 419 ± 209 U/mL, respectively,
p < 0.05). Serum KL-6 concentrations of the Ab+ group
were significantly higher than those of the Ab− group
(p < 0.001). In the Ab+ group, farmers with high serum
KL-6 concentrations had lower permeability coefficients than farmers
with normal serum KL-6 concentrations (p < 0.05). These results may
suggest that subclinical FLD can be detected in farmers with high KL-6
concentrations and precipitating antibodies.
Conclusion: Serum KL-6 concentration can be a useful marker
for assessing the activity of FLD and may be able to be used to detect