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→Mechanism of Acute Inflammation
However, in the case of acute inflammation, the response to an infection is dysregulated and often disproportional to the severity of the infection. The response gets overheated, overactivated, and can damage the body from within. Potential consequences of this overly strong reaction include infections, organ dysfunction (severe sepsis), or septic shock which is a state of circulatory failure where circulatory, cellular and metabolic abnormalities are associated with an increased risk of death. These reactions are often caused by coagulation (i.e. formation of blood clots) dysregulation. The hypercoagulability of sepsis is thought to be driven by the release of tissue factor from disrupted endothelial cells.<ref name="Arti13">Sepsis: The evolution in definition, pathophysiology, and management. SAGE Open Medicine, 7, 2050312119835043–2050312119835043, 2019, Gyawali, B., Ramakrishna, K., & Dhamoon, A. S., https://doi.org/10.1177/2050312119835043 </ref> When the human body suffers from severe sepsis, activated monocytes and endothelial cells, along with circulating microvesicles, become sources of tissue factor<ref name="Arti14">Role of extracellular vesicles in the development of sepsis-induced coagulopathy. Journal of Intensive Care, 6, 68, 2018, Iba, T., & Ogura, H., https://doi.org/10.1186/s40560-018-0340-6 </ref>.
This factor then causes the systemic activation of the coagulation cascade resulting in the production of thrombin, activation of platelets, and formation of platelet–fibrin clots. These structures can result in local perfusion defects leading to tissue hypoxia and organ dysfunction <ref name="Arti13">Sepsis: The evolution in definition, pathophysiology, and management. SAGE Open Medicine, 7, 2050312119835043–2050312119835043, 2019, Gyawali, B., Ramakrishna, K., & Dhamoon, A. S., https://doi.org/10.1177/2050312119835043 </ref>. Moreover, research has shown that dysregulated apoptotic immune cell-death plays a crucial part in immune dysfunction and mortality of sepsis. Apoptosis is a “programmed cell death” to limit damage of surrounding tissue during the immune response<ref name="Arti15">Apoptosis: a review of programmed cell death. Toxicologic Pathology, 35(4), 495–516, 2007, Elmore, S., https://doi.org/10.1080/01926230701320337 </ref>. It is a vital component of many processes in the human body such as cell turnover, proper development and functioning of the immune system ref name="Arti15">Apoptosis: a review of programmed cell death.<ref name="Arti15">Apoptosis: a review of programmed cell death. Toxicologic Pathology, 35(4), 495–516, 2007, Elmore, S., https://doi.org/10.1080/01926230701320337 </ref> Most cells that undergo enhanced apoptosis in sepsis are of lymphoid origin, hence less immune cells are left to fight off the infection itself <ref name="Arti16">Host–pathogen interactions in sepsis. The Lancet Infectious Diseases, 8(1), 32–43, 2008, van der Poll, T., & Opal, S. M., https://doi.org/https://doi.org/10.1016/S1473-3099(07)70265-7 </ref>. Since no effective treatment for sepsis exists yet, early diagnosis and recognition is crucial.<ref name="Arti17">Sepsis and septic shock: current approaches to management. Internal Medicine Journal, 49(2), 160–170., 2019, Thompson, K., Venkatesh, B., & Finfer, S., https://doi.org/10.1111/imj.14199 </ref>
This is where IL-6 plays an important part. As mentioned, IL-6 is a cytokine that functions as a crucial mediator during the acute phase of response to inflammation in sepsis.<ref name="Arti18">Diagnostic and prognostic value of interleukin-6, pentraxin 3, and procalcitonin levels among sepsis and septic shock patients: a prospective controlled study according to the Sepsis-3 definitions. BMC Infectious Diseases, 19(1), 968, 2019, Song, J., Park, D. W., Moon, S., Cho, H.-J., Park, J. H., Seok, H., & Choi, W. S., https://doi.org/10.1186/s12879-019-4618-7 </ref> Research on the clinical value of IL-6 in patients with sepsis and septic shock describes that IL-6 is considered controversial regarding its diagnostic and prognostic values, where meta-analysis of diagnostic value of IL-6 has shown that IL-6 only offers moderate success in differentiating sepsis from non-infectious systemic inflammatory response syndrome (SIRS).<ref name="Arti19">Role of interleukin-6 to differentiate sepsis from non-infectious systemic inflammatory response syndrome. Cytokine, 88, 126–135, 2016, Ma, L., Zhang, H., Yin, Y.-L., Guo, W.-Z., Ma, Y.-Q., Wang, Y.-B., Shu, C., & Dong, L.-Q., https://doi.org/10.1016/j.cyto.2016.08.033 </ref> Hence it is recommended that IL-6 is used as a biomarker to confirm infection rather than differentiate between sepsis and SIRS<ref name="Arti19">Role of interleukin-6 to differentiate sepsis from non-infectious systemic inflammatory response syndrome. Cytokine, 88, 126–135, 2016, Ma, L., Zhang, H., Yin, Y.-L., Guo, W.-Z., Ma, Y.-Q., Wang, Y.-B., Shu, C., & Dong, L.-Q., https://doi.org/10.1016/j.cyto.2016.08.033 </ref>.
|Sandwich
|-
|R&D Systems Incabcam|ab178013|Human IL-6 ELISA Kit|N/A|Serum, EDTA plasma, cit plasma, cell culture supernatants|7.8 - 500|D60501.6|Intra-assay CV = 2.1%, Inter-assay CV = 2.4%|90|ELISA|Sandwich|-|RayBio|ELH-IL6|Quantikine® RayBio® Human IL-6 ImmunoassayELISA Kit
|100
|Serum, plasma, or cell culture supernatants|3.1 0 - 3001000|3.0.7|Intra-assay: CV = 2.0% - 4.2< 10%, Inter-assay: CV = 3.8% - 6.4< 12%|270150
|ELISA
|Sandwich
|}<div style="margin-bottom:1em"><sub>''Table 1: Commercially available IL-6 well-plate assays.</sub><br />
Immunoassays, in general, provide a relatively slow method for measuring specific biomarkers like IL-6. Therefore, faster methods are the subject of intensive research. A commercially available rapid test is the Milenia® QuickLine IL-6 test: Milenia Biotec.<ref name="Arti27">Milenia Biotec, 2016, https://www.milenia-biotec.com/en/product/il6/#nav-overview </ref> This lateral flow immunoassay is designed for the semi-quantitative evaluation of human Interleukin-6 in serum, plasma, cell culture supernatant, amniotic fluid or cerebrospinal fluid.<ref name="Arti28">Rapid and sensitive detection of interleukin-6 in serum via time-resolved lateral flow immunoassay, Analytical Biochemistry, 588, 113468, 2020, Huang, D., Ying, H., Jiang, D., Liu, F., Tian, Y., Du, C., Zhang, L., & Pu, X., https://doi.org/10.1016/j.ab.2019.113468</ref><ref name="Arti29">Development of quantum dot-based fluorescence lateral flow immunoassay strip for rapid and quantitative detection of serum interleukin-6, Journal of Clinical Laboratory Analysis, 35(5), e23752, 2021, Tang, J., Wu, L., Lin, J., Zhang, E., & Luo, Y., https://doi.org/10.1002/jcla.23752 </ref> In the Milenia® QuickLine IL-6 test, the sample is pipetted in the sample application port. IL-6 of the patient's sample binds to a first monoclonal anti-IL-6 antibody conjugated to gold particles. The IL-6-loaded gold particles diffuse through the membrane and overflow the test line (T). There, a second monoclonal antibody specific for IL-6 is coated on the membrane; so the gold particles are bound specifically and become visible as a colored line. The color intensity is proportional to the concentration of IL-6 in the sample and intensifies during the incubation time. The surplus of gold particles continues to diffuse over the test strip. The conjugate specific antibodies printed as a control line on the membrane (control line, C) capture the gold conjugate and therefore a visible line develops during the incubation time.<ref name="Arti30">A Point of Care Lateral Flow Assay for Rapid and Colorimetric Detection of Interleukin 6 and Perspectives in Bedside Diagnostics, J Clin Med Res, 2(2), 1–16, 2020, de Souza Sene, I., Costa, V., Bras, D. C., de Oliveira Farias, E. A., Nunes, G. E., & Bechtold, I. H., https://doi.org/https://doi.org/10.37191/Mapsci-2582-4333-2(2)-032 </ref><ref name="Arti31">Duplex Shiny app quantification of the sepsis biomarkers C-reactive protein and interleukin-6 in a fast quantum dot labeled lateral flow assay, Journal of Nanobiotechnology, 18(1), 130, 2020, Ruppert, C., Kaiser, L., Jacob, L. J., Laufer, S., Kohl, M., & Deigner, H.-P., https://doi.org/10.1186/s12951-020-00688-1 </ref>
{| class="wikitable" style="margin-bottom:0"
!Company
!Product
!Test name
!Sample volume (μL)
!Sample matrix
!Range (pg/mL)
!Sensitivity (pg/mL)
!Incubation time (min)
!Measuring Technique
|-
|Milenia Biotec
|MQL6 1
|Milenia® QuickLine IL-6 test
|100
|Serum, plasma, cell culture supernatants, amniotic fluid, cerebrospinal fluid
|50 - 10000
|50
|20
|LFIA
|-
|}<div style="margin-bottom:1em"><sub>''Table 2: Commercially available rapid test, Milenia® Quickline IL-6 test.</sub><br />
== Safety & Lab protocols ==
<b>Safety</b>
Interleukin-6 is present in blood plasma, thus the sample preparation in the lab will also take place with human blood plasma as matrix. It is of crucial importance to handle human blood plasma with care due to potential pathogens that can be transmitted, such as Hepatitis viruses and HIV.<ref name="Arti32">Recommendations for the production, control and regulation of human plasma for fractionation, World Health Organization, 2007, https://www.who.int/bloodproducts/publications/TRS941Annex4blood.pdf </ref> Sigma Aldrich has screened the blood plasma in advance on HIV, Hepatitis B and Hepatitis C, however caution is recommended all the same.<ref name="Arti33">Plasma from human, Sigma Aldrich, Retrieved November 12, 2021 from https://www.sigmaaldrich.com/NL/en/product/sigma/p9523, n.d. </ref> Specific lab protocols and rules will be listed below.
<b>Lab protocols</b>
During the preparation of the blood samples, one should avoid physical contact with blood by wearing gloves, glasses, and lab coats. Needles and lancets should be used only once and disposed of in a sharps container for decontamination.<ref name="Arti34">Serum / Plasma Specimens - Safety, Centers for Disease Control and Prevention, 2016, https://www.cdc.gov/dpdx/diagnosticprocedures/serum/safety.html </ref> Furthermore, cuts already present on hands or arms should be covered with plasters to avoid blood-on-blood contact. After completing the samples, gloves should be removed and hands should be washed thoroughly.<ref name="Arti34">Serum / Plasma Specimens - Safety, Centers for Disease Control and Prevention, 2016, https://www.cdc.gov/dpdx/diagnosticprocedures/serum/safety.html </ref> The waste should be disposed of in specific biohazard waste bins or bags.
Il-6 will be provided by HyTest. Instructions for storage will also be provided by HyTest. In general, human interleukin-6 is not a dangerous substance according to GHS ((Globally Harmonized System of Classification and Labeling of Chemicals).<ref name="Arti35">Safety Data Sheet - Recombinant Human Interleukin-6 (IL-6), BioVision Inc., 2015, https://www.biovision.com/documentation/sds/4143_SDS.pdf</ref> Potential health effects include:
== References ==
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