ED-COMP200

Introduction
The Wieslab® COMP is an enzyme immunoassay for quantitation of intact or fragmented human Cartilage Oligomeric Matrix Protein (COMP) in serum or synovial fluid. The assay serves as an indicator of cartilage turnover. COMP is a high molecular weight, multi-subunit protein originally isolated from cartilage (1, 2). The protein is abundant in cartilage but is also found in tendon and other tissues (3). The protein belongs to the thrombospondin family (4). Measurement of intact COMP and fragments thereof in synovial fluid or serum have been shown to correlate to cartilage destruction in rheumatoid arthritis and osteoarthritis patient studies (5, 6, 7). In synovial fluid COMP is present to some extent as an apparently intact protein but the majority is found as several different fragments (8). In serum the fragments are 50-90 kDa. The exact composition of the fragments is still unknown.

For research use only.

Assay principle
The assay utilizes native human articular cartilage COMP which has been coated to 96-well microtiter plates and a rabbit polyclonal antiserum directed to human COMP. It is in standard ELISA inhibition format with an overnight preincubation step with sample and primary antiserum. After the over night preincubation step the solution is transferred to the COMP coated plate. Bound antibody is detected using an alkaline phosphatase labeled anti rabbit IgG conjugate. Recommended dilution of serum samples is 1/50 and for synovial fluids 1/500.

Kit contents
The kit contains all the reagents necessary for 40 determinations in duplicate.
- 96-well round bottom preincubation plate
- 12 x 8-well strips coated with COMP with lid
- one set of calibrators (10, 20, 30, 40, 60, 80 ng/ml), sufficient for three calibrator curves
- two prediluted control sera
- sample dilution buffer
- preincubation buffer with anti-COMP reagent
- alkaline phosphatase labeled conjugate directed against rabbit IgG
- 30x concentrated wash buffer
- substrate buffer
- substrate tablets

Expected results
COMP levels in unselected blood donors age 22-59 were found to be 1.35 ± 0.40 µg/ml (range 0.99 - 2.54). No normal values are available for synovial fluids but in a clinical material of knee synovial fluids from knee trauma patients COMP ranged from 14 to 48 µg/ml.

Performance characteristics
Intra-assay precision was determined by testing the two serum samples in duplicate. Each sample was assayed 20 times on the same plate. Shown are serum concentrations expressed as µg/ml.