INTENDED USE

This Human MCP-3 ELISA Kit is to be used for the in vitro quantitative determination of human monocyte chemotactic protein-3 (MCP-3) concentrations in serum, plasma, cell culture supernatant, and other biological fluids. This kit is intended for LABORATORY RESEARCH USE ONLY and is not for use in diagnostic or therapeutic procedures.

INTRODUCTION

Monocyte Chemotactic Protein (MCP-3) is a novel chemokine that has been recently purified from human osteosarcoma cell line¹. It was shown that MCP-3 is produced by both tumours cells¹ and leukocytes.^2,3 MCP-3 can bind and activate a vast diversity of inflammatory cell types through interaction with multiple leukocyte receptors as well as it’s own receptor.^6,7 Murine MCP‑3 Marc/Fic chemokines that have been previously cloned are thought to be homologues of human MCP-3.^3,4 MCP-3 cDNA cloning² and structural analysis revealed that this 76 amino acid (a.a.) polypeptide with a molar mass of 8.5 kDa belongs to a family of small inflammatory proteins, characterized by four conserved cysteine residues and is localized on human chromosome 17.^1,4,5 MCP-3 is designated a C-C or intercrine ß cytokine.¹³ MCP-3 can indeed use a wide variety of binding sites and activate many inflammatory cells. In vitro, both MCP-3 and MCP-1 can activate T-cells, monocytes, and basophils, but only the first can activate eosinophils. These cytokines show 71% a.a. homology. MCP‑3 was also revealed to have 30% a.a homology with MIP-1 and RANTES which can also activate eosinophils plus all cell types mentioned above.^6,7 MCP-3 seems to be the only C-Cchemokine that regularly induces neutrophil migration. It is also a potent chemoattractant for human dendritic cells.⁷

It has been suggested that MCP-3 binds multiple C-C receptors such as MCP-1 on monocytes and basophils ^8,9, MIP-1a on neutrophils, basophils, and eosinophils⁹ and RANTES on basophils and eosinophils^(9,10). Evidence suggests that MCP-3 does indeed use multiple receptors (MCP-1, RANTES, and MIP-1a) and binds with MIP-1ß receptor as well as other unique binding sites ^6,7.MCP-3 was discovered to be the strongest C‑Cchemokine in inducing the migration of C-C CKR1 transfected cells. It was shown that MCP-3 binds with C-C CKR1 receptor with greater affinity than MIP‑1a or Rantes, which mainly activate it ^6,11. Also, MCP-3 promotes exocytosis of eosinophil granule proteins and stimulates histamine release from human basophils ^4,12. In vivo, MCP-3 induces the selective infiltration of monocytes on intradermal injection in rabbits.¹ Since MCP-3 acts on a variety of inflammatory cells and utilizes multiple receptors for its function, characterization and isolation of the shared as well as unique receptors for MCP-3 will provide further insights into the pathophysiological roles of MCP-3. C-C chemokines are mediators of a number of pathological conditions such as chronic inflammation, tumor, allergy, as well as atherosclerosis¹⁰. Since the binding and signaling of MCP-3 is most promiscuous, the development of antibody or antagonist which can block MCP-3 through binding to the receptor or ligand may prove to be useful in the treatment of diseases mediated by a number of C-C chemokine.

This MCP-3 ELISA is a 2.5 hour solid phase immunoassay readily applicable to measure MCP-3 in serum, plasma, cell culture supernatant, and other biological fluids in the range of 0 to 1600 pg/mL. It showed no cross-reactivity with other cytokines tested. MCP-3 may play a role in certain diseases, therefore this MCP-3 ELISA is expected to be effectively used for further investigations into the relationship between MCP-3 and various pathological conditions.