Complement Function/Activity Test
Complement function or activity test allows for the determination of whether the protein is present and whether it has normal functional activity. A wide range of assays are now available in Creative Biolabs, such as Hemolysis assays (CH50 or AH50), Elisa Assays (c3a, c5a, FH, FB, C5b-9 or others), Complement Inhibitor Validation (IC50)......
The lectin complement pathway is an essential part of the complement system, which provides an effective defense against invading pathogens and apoptotic cells in an organism. Similar to classical pathway, the lectin pathway is also a proteolytic cascade that elicits various effector functions including phagocytosis, cell lysis, inflammation, and guidance of the adaptative immune response.
Lectin Complement Pathway
The lectin pathway is initiated when one of the pattern recognition receptors (PRRs) binds to pathogen-associated molecular patterns (PAMPs) (D-mannose, N-acetyl-D-glucosamine, or acetyl groups), on the surface of invading microorganisms or apoptotic/necrotic cells. The well-characterized PRRs include mannose-binding lectin (MBL), ficolins and collagen-containing soluble C-type lectins (collectins), such as kidney collectin-11 (CL-K1). These circulated lectins are complexed with serine proteases named MBL-associated serine proteases (MASPs), comprising MASP-1, -2, and -3. The enzymatic cascade is really started after the binding of MBL/MASPs, CL-K1/MASPs, or ficolin/MASPs complexes to their targets.
Fig 1. The Structural subunits of MBL and ficolins. (Beltrame, et al. 2015)
The Activation Steps of Lectin Complement Pathway
The domain structures of MASPs resemble C1r and C1s in the classical pathway, so their activation steps are very similar. Like C1s, MASP-2 contributes to the generation of C3 convertase via subsequent cleavage of C4 (C4a+C4b) and C2 (C2a+C2b). The cleaved product C4b and C2a is membrane- associated, and they can combine to form C4bC2a (C3 convertase) to trigger the downstream integrated enzyme reaction. The activation of MASP-2 is dependent on MASP-1. C3 convertase can cleave C3 to C3b, which unites C4bC2a to form C5 convertase (C4bC2aC3b). C5 convertase dissociates C5 to C5a and C5b, initiating the assembly of the membrane-attack complex (MAC). C5b recruits C6, C7, C8, C9 to form a fully functional MAC, resulting in cell lysis and death.
Fig 2. The activation of lectin pathway. (Mason, et al. 2015)
Creative Biolabs provides customized services based on the lectin pathway targets, including:
Our comprehensive complement platform offers a great number of complement-related products in a rapid and cost-effective manner. If you are interested, please feel free to contact us for more details.
1. Beltrame, M. H.; et al. (2015). The lectin pathway of complement and rheumatic heart disease. Frontiers in pediatrics. 2: 148.
2. Mason, C. P.; Tarr, A. W. (2015). Human lectins and their roles in viral infections. Molecules. 20(2), 2229-2271.