Calprotectin in Serum

The sCAL ELISA is a micro-titre based assay kit for determination of the dimeric format of calprotectin in serum samples. All reagents, standards and controls are provided in one kit and are in a ready to use format. There is no requirement for reconstituting any component, apart from the wash buffer so this minimises any errors and ensures a long shelf life. The ELISA can be performed manually or on a DS2 automated processor to reduce hands–on time in higher throughput environments.

• Helping to Manage Juvenile Idiopathic Arthritis
Great Ormond Street Hospital User Report – Serum Calprotectin Monitoring
https://a.storyblok.com/f/93856/x/edf6fb87db/serum-calprotectin_user_report_le-summer16.pdf

•  To establish a test for MRP8/14 protein in childhood arthritis
Ahmed et al. Great Ormond Street Hospital
https://www.calprotectin.co.uk/wp/wp-content/uploads/2023/07/17-Ahmed-To-establish-a-test-for-MRP814-protein-in-childhood-arthritis-3.pdf

• Hurnakova: Serum calprotectin discriminates subclinical disease activity from ultra-sound defined remission in patients with RA in clinical remission
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5104448/pdf/pone.0165498.pdf
Shows the “potential ability of serum calprotectin to discriminate ultrasound-defined remission from subclinical disease activity in RA patients who have achieved clinical remission. Overall, this study suggests that calprotectin might represent a valuable serological biomarker for confirming deep remission in RA patients”

• 21 Park et al: MRP8/14 serum levels as diagnostic markers for systemic juvenile idiopathic arthritis in children with prolonged fever. Rheumatology 2021; 00: 1-11
https://pubmed.ncbi.nlm.nih.gov/34559193/
“Rapid results may enable effective treatment within a window of opportunity preventing disease progression” (sensitivity 84%, specificity 81%):

• Ma et al: Serum Calprotectin Can Differentiate Between Sustained Remission and Low Disease Activity States in Rheumatoid Arthritis. ACR Paediatric Rheumatology symposium
https://acrabstracts.org/abstract/serum-calprotectin-can-differentiate-between-sustained-remission-and-low-disease-activity-states-in-rheumatoid-arthritis/
This study demonstrated the role of calprotectin in differentiating subtle low disease activity states. Serum calprotectin was significantly different between low disease activity and remission as defined using different remission criteria. Its utility was seen with point remission as well as longitudinally over 1 year.

• La et al: Serum calprotectin (S100A8/A9): a promising biomarker in diagnosis and follow-up in different subgroups of juvenile idiopathic arthritis
https://rmdopen.bmj.com/content/rmdopen/7/2/e001646.full.pdf
This study confirms the interest of sCal as a potential marker of response to treatment or risk of flares. It also highlights its role as a useful diagnostic tool and marker of disease activity, with a greater specificity than with C-reactive protein.

• Marushko et al: Evaluation of serum calprotectin (MRP-8/MRP-14) levels in patients with juvenile idiopathic arthritis
https://jpnim.com/index.php/jpnim/article/view/e100140
sCal levels should be used to monitor the subclinical inflammatory activity in patients with JIA.

The BÜHLMANN sCAL® turbo is an in vitro diagnostic test designed for the quantitative determination of the tetrameric format of calprotectin (MRP8/14) in human serum samples to avoid the background calprotectin that will be found in standard blood samples. This is the dominant format found in serum due to the high and even distribution of calcium.

The BÜHLMANN sCAL® turbo test is a particle enhanced turbidimetric immunoassay (PETIA) and allows quantification of calprotectin in human serum samples on clinical chemistry analysers. Samples can be measured without any additional dilution steps and are incubated with reaction buffer and mixed with polystyrene nanoparticles coated with calprotectin-specific antibodies (immunoparticles). Any calprotectin available in the sample mediates immunoparticle agglutination and sample turbidity which is measured by light absorbance. The detected light absorbance allows quantification of calprotectin concentration via interpolation on an established calibration curve.

Assay standardisation:

The BÜHLMANN sCAL® turbo is standardized against internal reference material (purified native calprotectin). Calibrator and control values are assigned according to a value transfer protocol (ref. 1, 2), to guarantee metrological traceability. The analytical measuring interval of the BÜHLMANN sCAL® turbo, established on the Mindray BS-480 instrument, is 0.23-15.0 μg/mL.

Sample Collection:

Blood can be collected into a serum tube or a gel separator tube, once clotted the tubes are centrifuged at 1800g for 15 minutes and then the serum transferred into a plain tube. This then prevents the contamination of the sample with un-released calprotectin which would cause higher values. Once separated the samples can be stored at 2-8C for 16 days or for 1 month at -20C.

Reference Interval:

The reference interval of the BÜHLMANN sCAL® turbo assay was established according to CLSI C28-A3 with 160 serum samples from self-declared healthy individuals: adult men and women aged 18 to 83 years. The samples were collected either in native tube or tube with gel separator and processed within 3-4 hours after collection.

• A novel Serum Calprotectin (MRP8/14) particle enhanced immuno-turbidimetric assay (sCAL turbo) helps to differentiate SJIA from other diseases in routine clinical laboratory settings
https://www.calprotectin.co.uk/wp/wp-content/uploads/2023/11/23-Foell-A-novel-serum-calprotectin-PETIA-helps-to-differentiate-SJIA-from-other-diseases-in-rouitine-clinical-lab-Ann-Rheum-Dis_Full.pdf
The sCAL turbo assay showed an excellent correlation to the MRP8/14 ELISA used in the previous validation studies (r=0.99, p<0.001). It could reliably differentiate SJIA from all other diagnoses with significant accuracy (cut-off at 9,100 ng/ml, sensitivity 93%, specificity 87%, ROC area under curve 0.961 p<0.001).