Circulating cytokeratin 8:anti-cytokeratin 8 antibody immune complexes in sera of patients with pulmonary fibrosis.
BACKGROUND
It has been suggested that the humoral immune system plays a role in the pathogenesis of idiopathic pulmonary fibrosis (IPF) and pulmonary fibrosis associated with collagen vascular disorders (PF-CVD). Although circulating immune complexes in patients' sera have been suggested, none of the antigens have been characterized.


OBJECTIVE
The purpose of this study is to characterize the antigen of the immune complexes in patients' sera of pulmonary fibrosis.


METHODS
As we previously established that one of the antibodies against A549 cells (lung alveolar type II cells) was anti-cytokeratin 8 (CK8), we confirmed the existence of anti-CK8 antibody in patients' sera by Western immunoblot. In addition, we tried to demonstrate circulating CK8:anti-CK8 immune complexes in patients' sera by Western immunoblot. Furthermore, we established an enzyme-linked immunosorbent assay to quantitate CK8:anti-CK8 immune complexes.


RESULTS
In patients with pulmonary fibrosis, anti-CK8 antibodies were clearly demonstrated in sera by Western immunoblot. In addition, circulating CK8:anti-CK8 immune complexes were also clearly demonstrated by Western immunoblot. It was possible to establish ELISA to quantitate CK8:anti-CK8 immune complexes. If the cutoff value, which was determined based on the highest value of normal volunteers, was introduced, high CK8:anti-CK8 antibody complexes were demonstrated in 9 of 31 patients (29.0%) with IPF and PF-CVD.


CONCLUSIONS
This is the first study to clarify the antigen of the circulating immune complex in sera of patients with IPF. These results suggest that circulating CK8:anti-CK8 immune complexes may have played a role in the process of lung injury in pulmonary fibrosis.
First Department of Internal Medicine, Kagawa Medical University, Kita-gun, Kagawa, Japan.
N
N
Dobashi
J
J
Fujita
Y
Y
Ohtsuki
I
I
Yamadori
T
T
Yoshinouchi
T
T
Kamei
M
M
Tokuda
S
S
Hojo
S
S
Bandou
Y
Y
Ueda
J
J
Takahara
D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood*; D000936:Antigen-Antibody Complex / Q000097:blood*; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007633:Keratins / Q000097:blood* / Q000276:immunology*; D008875:Middle Aged; D011658:Pulmonary Fibrosis / Q000097:blood* / Q000276:immunology*
D000906:Antibodies; D000936:Antigen-Antibody Complex; D007633:Keratins