Description

Nori Equine CXCL4 ELISA Kit Summary

Alternative names for CXCL4: chemokine (C-X-C motif) ligand 4, PF4, platlet factor 4, PF-4

Alternative names for equine: horse

Standard Curve

Kit Components
1. Pre-coated 96-well Microplate
2. Biotinylated Detection Antibody
3. Streptavidin-HRP Conjugate
4. Lyophilized Standards
5. TMB One-Step Substrate
6. Stop Solution
7. 20 x PBS
8. Assay Buffer

Other Materials Required but not Provided:
1. Microplate Reader capable of measuring absorption at 450 nm
2. Log-log graph paper or computer and software for ELISA data analysis
3. Precision pipettes (1-1000 µl)
4. Multi-channel pipettes (300 µl)
5. Distilled or deionized water

Protocol Outline
1. Prepare all reagents, samples and standards as instructed in the datasheet.
2. Add 100 µl of Standard or samples to each well and incubate 1 h at RT.
3. Add 100 µl of Working Detection Antibody to each well and incubate 1 h at RT.
4. Add 100 µl of Working Streptavidin-HRP to each well and incubate 20 min at RT.
5. Add 100 µl of Substrate to each well and incubate 5-30 min at RT.
6. Add 50 µl of Stop Solution to each well and read at 450 nm immediately.

Background: 

Platelet factor 4 (PF4) is a small cytokine belonging to the CXC chemokine family that is also known as chemokine (C-X-C motif) ligand 4 (CXCL4) and is encoded by PF4 gene.[1] This chemokine is released from alpha-granules of activated platelets during platelet aggregation, and promotes blood coagulation by moderating the effects of heparin-like molecules. It is usually found in a complex with proteoglycan. Platelet factor-4 is a 70-amino acid protein that is released from the alpha-granules of activated platelets and binds with high affinity to heparin. Its major physiologic role appears to be neutralization of heparin-like molecules on the endothelial surface of blood vessels, thereby inhibiting local antithrombin activity and promoting coagulation. As a strong chemoattractant for neutrophils, monocytes and fibroblasts, PF4 probably has a role in inflammation and wound repair.^[2] PF4 interacts with a splice variant of the chemokine receptor CXCR3, known as CXCR3B.^[3] The heparin:PF4 complex is the antigen in heparin-induced thrombocytopenia, an idiosyncratic autoimmune reaction to the administration of the anticoagulant heparin.^[4] PF4 autoantibodies have also been found in patients with thrombosis and features resembling HIT but no prior administration of heparin.^[5] It is increased in patients with systemic sclerosis that also have interstitial lung disease.^[6] The Canine PF4 kills malaria parasites within erythrocytes by selectively lysing the parasite’s digestive vacuole.^[7] Study elucidate an unanticipated mechanism for CXCL4-mediated immune amplification in systemic sclerosis, in which CXCL4 organizes ‘self’ and microbial DNA into liquid crystalline immune complexes that amplify TLR9-mediated plasmacytoid dendritic cell hyperactivation and interferon-alpha production. Surprisingly, this activity does not require CXCR3, the CXCL4 receptor.[8] Non-platelet-derived CXCL4 differentially regulates cytotoxic and regulatory T cells through CXCR3 to suppress the immune response to colon cancer.[9] Observations suggest the crucial role of platelet cytokine PF4 as the rapid enhancer of replication as well as propagation of both observations together suggest the crucial role of platelet cytokine PF4 as the rapid enhancer of replication as well as propagation of both Dengue virus and Japanese Encephalitis virus in host cells including monocytes by inhibiting IFN response of these immune cells.[10]

References

1. Deuel TF, et al. (1977).  Proc. Natl. Acad. Sci. U.S.A. 74 (6): 2256–2258.
2. Eisman R, et al. (1990). Blood. 76 (2): 336–44.
3. Lasagni L, et al. (2003). J Exp Med. 197 (11): 1537–1549.
4. Warkentin TE (2007). N. Engl. J. Med. 356 (9): 891–893.
5. Warkentin TE, et al. (2008). Am. J. Med. 121 (7): 632–636.
6. Volkmann ER, et al. (2016). Arthritis Research & Therapy. 18 (1): 305.
7. Love MS, et al. (2012). Cell Host Microbe. 12 (6): 815–23.
8. Lande R, et al (2019) Nat Commun 10 (1), 1731.
9. Deng S, et al. (2019) Cancer Lett. 443, 1-12.
10. Ojha A, et al. (2019) EBioMedicine 39, 332-347.

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