OBJECTIVES:
Type VIII collagen is involved in angiogenesis and remodeling of arteries. We hypothesized that type VIII collagen was upregulated in diseases associated with vascular remodeling, e.g. pulmonary fibrosis and cancer. In this paper we present the development and validation of a competitive enzyme-linked immunosorbent assay (ELISA) targeting type VIII collagen in serum and plasma.

DESIGN AND METHODS:
A monoclonal antibody was raised against the C-terminal of type VIII collagen (C8-C) and a competitive ELISA was developed. The assay was evaluated in relation to epitope specificity, technical performance, and in relevant disease cohorts. The developed ELISA was applied for the assessment of type VIII collagen in serum from patients diagnosed with chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF) and various cancers.

RESULTS:
The C8-C ELISA was technically stable and applicable for measurements in serum and plasma samples. Concentrations of C8-C was increased in serum from patients diagnosed with COPD (n=68) (p<0.0001), SCC lung- (n=10) (p<0.0001), breast- (n=13) (p<0.0001), colon- (n=7) (p=0.002), melanoma- (n=7) (p=0.001), non-small cell lung- (n=12) (p<0.0001), ovary- (n=10) (p=0.0001), pancreas- (n=5) (p=0.017), prostate- (n=14) (p=0.001) and small cell lung cancer (n=8) (p=0.0002) when compared to controls (n=43). Concentrations of C8-C were not significantly increased in serum from patients diagnosed with IPF.

CONCLUSIONS:
The C8-C assay was technically robust and specific for type VIII collagen. Concentrations of C8-C were significantly elevated in serum from patients diagnosed with COPD and within 9 different cancer types, but not IPF. Further research is required to test C8-C as an efficacy marker for angiostatic treatments.