Assay | Target molecule | Short description | Evidence of potential usefulness |
---|---|---|---|
KS/mAb OA-1 | Aggrecan | Cartilage degradation. Sandwich ELISA using mAb to keratan sulfate and mAb OA-1 to AGase neoepitope ARGSVIL [143]. Detection of fragments in human synovial fluid [143] | [143] |
CS846 | Aggrecan | Cartilage turnover. mAb αHFPG-846 (IgM) recognizing chondroitin sulfate moieties on aggrecan. Manufacturer: Ibex, Canada | |
342-G2 | Aggrecan | Cartilage degradation. Sandwich ELISA using mAb AF28 binding to the neoepitope 342FFGVG and monoclonal antibody F78 binding to G1/G2 for detection of MMP-generated aggrecan fragments | [45] |
G1-G2 | Aggrecan | Cartilage turnover. Sandwich ELISA using mAb F78 binding to G1/G2 both as capture and detector antibody for detection of intact aggrecan and all aggrecan fragments carrying G1 and/or G2 | |
Serum CRP | C-reactive protein | General inflammation. CRP, an acute phase protein, the assay for which is highly sensitive to detect small changes in magnitude of inflammation | |
COMP | Cartilage oligomeric protein | Cartilage turnover. Competition ELISA using polyclonal antibodies [58]. However, sandwich ELISA based on two monoclonal antibodies recognizing different antigenic determinants is described [150]. Manufacturer: AnaMar Medical, Sweden | |
PICP | Carboxyl terminus propeptide of type I procollagen | Bone formation. RIA using polyclonal antibodies raised to fibroblast PICP digested with bacterial collagenase [156]. Manufacturer: Orion Diagnostic, Finland | [156] |
PINP | Amino terminus propeptide of type I procollagen | Bone formation. RIA using polyclonal antibodies recognizing PINP [157]. Manufacturer: Orion Diagnostic, Finland. Electrochemiluminecense using mAbs to PINP. Manufacturer: Roche Diagnostics, Germany | [158] |
CTX-I | Type I collagen | Bone resorption. A sandwich ELISA using mAb F1103 and F12, both binding to a cathepsin K-derived C-telopeptide neoepitope EKAHD-β-GGR, where D-β-G denotes an isomerized linkage between D and G [84]. Manufacturer: IDS, UK. Also available in an automated version (manufacturer: Roche Diagnostics, Germany) | |
NTX-I | Type I collagen | Bone resorption. EIA detecting a fragment of the N-telopeptide of type I collagen. Manufacturer: Inverness, US | [159] |
ICTP | Type I collagen | MMP-mediated type I collagen type degradation. RIA detecting a fragment of the C-telopeptide of type I collagen. Manufacturer: Orion Diagnostic, Finland | |
PIINP | Amino terminus propeptide of type II procollagen | Cartilage formation. mAb recognizing the amino acid sequence GPQPAGEQGPRGDR located in the amino-terminal propeptide of type II procollagen [46] | [46] |
PIIANP | Amino terminus propeptide of type II procollagen, splice variant A | Cartilage formation. An ELISA using rabbit polyclonal antibodies raised to recombinant exon-2 of the amino-terminal propeptide of type II procollagen | [71] |
CPII | C-propeptide of type II collagen | Cartilage formation. EIA using rabbit polyclonal antibodies binding to the C-propeptides of type II collagen, that is, a marker of collagen synthesis. Manufacturer: Ibex, Canada | [161] |
9A4/5109 | Type II collagen | Cartilage degradation. The collagenase-derived neoepitope GEGAAGPSGAEGPPGPQG775 containing the carboxyl terminus of the long three-quarter fragment. mAb 5109 detects the first underlined sequence, mAb 9A4 the second (neoepitope) | [162] |
CTX-II | Type II collagen | Cartilage degradation. Competition ELISA using mAb F4601 recognizing the C-telopeptide neoepitope EKGPDP (manufacturer: IDS, UK) and mAb 2B4 recognizing the C-telopeptide neoepitope EKGPDP | |
uTIINE | Type II collagen | Cartilage degradation. An LC-MS/MS assay using mAb 5109 (see above) to affinity purify fragments subjected to MS/MS. Detects a collagenase-derived 45-mer containing the carboxyl terminus of the long three-quarter fragment | |
HELIX-II | Type II collagen | Cartilage degradation. A competition ELISA using polyclonal rabbit antibodies recognizing the neoepitope 622ERGETGPP*GTS632, where P* denotes hydroxyproline. However, a recent publication has highlighted unspecificities [164] | |
C2C | Type II collagen fragment | Cartilage degradation. EIA using a monoclonal antibody recognizing the carboxyl terminus of the three-quarter piece of the degraded alpha1(II) chain. Manufacturer: Ibex, Canada | |
C1,C2 | Type II collagen fragment | Collagen degradation. EIA using rabbit polyclonal antibodies binding to the carboxy-terminal (COL2-3/4C(short)) neoepitope generated by cleavage of native human type II collagen by collagenases. Cross-reactivity to type I collagen | [169] |
PIIINP | Amino terminus propeptide of type III procollagen | Collagen type II formation. RIA using polyclonal antibodies recognizing PIIINP. Manufacturer: Orion Diagnostic, Finland | [170] |
Glc-Gal-PYD | Glucosyl-galactosyl-pyridinoline | Synovial inflammation. HPLC method for determination of the non-reducible collagen cross-linker glucosyl-galactosyl-pyridinium present in synovium and absent in bone cartilage and other soft tissue | [171] |
Serum HA | Hyaluronic acid | Cartilage turnover. Based on HA binding protein isolated from bovine cartilage. Manufacturer: for example, Pharmacia, Sweden | Â |
YKL-40 | Human glycoprotein 39 | Cartilage turnover. RIA using polyclonal antibodies to a 40 kDa glycoprotein. A combined monoclonal capture and polyclonal (rabbit) detector sandwich assay is available. Manufacturer: Quidel Corporation, US | [172] |
OC | Osteocalcin | Bone formation. Numerous assays available | Â |
MMP-3 and MMPs | Varous cell types | Numerous assays available | |
DKK1/Sclerostin | Dkk-1 | Measurement of Wnt signaling | |
TRACP 5a | Macrophages | Inflammation | [111] |
TRACP 5b | Osteoclasts | Osteoclast number. mAb to TRAcP 5b, which may be specific for osteoclasts but not their activity | |
Cat K | Osteoclasts | Osteoclast number | [110] |