Complement C3/C3a Protein, Human

Complement C3/C3a protein plays a key role in initiating the complement system through processing by C3 convertase in both the classical and alternative pathways. Complement C3/C3a protein is involved in various immune and inflammatory responses and also has a role in regulating blood pressure. Complement C3/C3a Protein, Human is a recombinant Complement C3/C3a protein expressed in E. coli, untagged, and consists of 77 amino acids (S672-R748)^{[1][2][3][4][5][6][7][8][9][10][11]}.

Complement C3 can be cleaved by C3 convertases or by blood proteases (such as thrombin) and immune cell-derived proteases (such as cathepsins) at sites of inflammation, producing two split products: Complement C3/C3a and Complement C3/C3b. Complement C3/C3a participates in various immune and inflammatory responses and exhibits bidirectional effects in different immune cells, potentially influencing immune responses and disease processes through different mechanisms^[1][2].
(a) In monocytes and macrophages, Complement C3/C3a mediates through TLR-4, promoting the production of pro-inflammatory mediators such as IL-1β, TNF-α, IL-6, and PGE2. (b) In mast cells, Complement C3/C3a induces histamine degranulation. (c) In eosinophils, it stimulates calcium mobilization, oxidative burst, and degranulation. (d) Additionally, Complement C3/C3a reduces neutrophil migration into the bloodstream by inhibiting mobilization factors. (e) Complement C3/C3a also plays a crucial role in brain inflammation by activating brain endothelial cells and recruiting leukocytes. (f) Complement C3/C3a can directly or indirectly alter T cell responses through interaction with receptors C3aR on antigen-presenting cells (APCs) and T cells^[3][4][5][6].
Complement C3/C3a is present in plasma-derived FVIII products and can promote T cell proliferation mediated by pdFVIII (FVIII products extracted from plasma) and lipopolysaccharides (HY-D1056) in dendritic cells (DCs)^[7].
Additionally, Complement C3 is reported to have antioxidant stress activity, protecting human bronchial epithelial cells from cigarette smoke-induced oxidative stress and inhibiting apoptosis^[7].

Complement C3/C3a (Human) (2 μg/mL) increases the expression of NF-κB and IL-1β in human podocytes^[9].
Complement C3/C3a (Human) (200 ng/mL, 2 hours) upregulates the expression of VCAM-1 and ICAM-1 in mouse primary cerebral endothelial cells induced by Lipopolysaccharides (HY-D1056) through the activation of p38 MAPK and NF-κB phosphorylation, thereby exerting an anti-inflammatory effect^[11].

Complement C3/C3a (Human) receptor antagonist (JR14a) (10 mg/kg, i.g., once daily for 7 days) can reduce proteinuria levels in the Heymann nephritis rat model induced by anti-Fx1A antibodies, indicating that C3a is a pro-inflammatory factor in this model^[9].

Measured by its ability to enhance IL-6 secretion by THP-1 human acute monocytic leukemia cells. The ED₅₀ for this effect is ≤0.4476 μg/mL, corresponding to a specific activity is ≥2234.1376 U/mg.

• 
  Measured by its ability to enhance IL-6 secretion by THP-1 human acute monocytic leukemia cells. The ED₅₀ for this effect is 0.1759 μg/mL, corresponding to a specific activity is 5685.0483 U/mg.

Human

E. coli

Tag Free

P01024 (S672-R748)

718  [NCBI]

SVQLTEKRMDKVGKYPKELRKCCEDGMRENPMRFSCQRRTRFISLGEACKKVFLDCCNYITELRRQHARASHLGLAR

Approximately 13.0 kDa

• 
  Greater than 95% as determined by reducing SDS-PAGE.

Lyophilized powder

Lyophilized from a 0.2 μm filtered solution of 20 mM PB, 150 mM NaCl, pH 7.4.

<1 EU/μg, determined by LAL method.

It is not recommended to reconstitute to a concentration less than 100 μg/mL in ddH₂O. For long term storage it is recommended to add a carrier protein (0.1% BSA, 5% HSA, 10% FBS or 5% Trehalose).

Stored at -20°C for 2 years. After reconstitution, it is stable at 4°C for 1 week or -20°C for longer (with carrier protein). It is recommended to freeze aliquots at -20°C or -80°C for extended storage.

Room temperature in continental US; may vary elsewhere.

• [1]. Coulthard LG, et al. Is the complement activation product C3a a proinflammatory molecule? Re-evaluating the evidence and the myth. J Immunol. 2015 Apr 15;194(8):3542-8.  [Content Brief]

  [2]. Markiewski MM, et al. Complement and coagulation: strangers or partners in crime? Trends Immunol. 2007 Apr;28(4):184-92.  [Content Brief]

  [3]. Wu F, et al. Complement component C3a plays a critical role in endothelial activation and leukocyte recruitment into the brain. J Neuroinflammation. 2016 Jan 28;13:23.  [Content Brief]

  [4]. Kubota Y. 1992. The effect of human anaphylatoxins and neutrophils on histamine release from isolated human skin mast cells. J. Dermatol. 19: 19–26.

  [5]. Asgari E., et al. 2013. C3a modulates IL-1β secretion in human monocytes by regulating ATP efflux and subsequent NLRP3 inflammasome activation. Blood 122: 3473–3481.

  [6]. Daffern P. J., et al. 1995. C3a is a chemotaxin for human eosinophils but not for neutrophils. I. C3a stimulation of neutrophils is secondary to eosinophil activation. J. Exp. Med. 181: 2119–2127.

  [7]. Ringler E, et al. Complement protein C3a enhances adaptive immune responses towards FVIII products. Haematologica. 2023 Jun 1;108(6):1579-1589.  [Content Brief]

  [8]. Pei Y, et al. Complement component 3 protects human bronchial epithelial cells from cigarette smoke-induced oxidative stress and prevents incessant apoptosis. Front Immunol. 2022 Dec 20;13:1035930.  [Content Brief]

  [9]. Gao S, et al. Complement C3a and C3a Receptor Activation Mediates Podocyte Injuries in the Mechanism of Primary Membranous Nephropathy. J Am Soc Nephrol. 2022 Sep;33(9):1742-1756.  [Content Brief]

  [10]. Lillegard KE, et al. Differential effects of complement activation products c3a and c5a on cardiovascular function in hypertensive pregnant rats. J Pharmacol Exp Ther. 2014 Nov;351(2):344-51.  [Content Brief]