Lectin pathway

lectinMannan-binding lectin pathwaylectin complement pathwaymannose-binding lectin pathway
The lectin pathway is a type of cascade reaction in the complement system, similar in structure to the classical complement pathway, in that, after activation, it proceeds through the action of C4 and C2 to produce activated complement proteins further down the cascade.wikipedia
43 Related Articles

Classical complement pathway

classicalclassical pathwayclassical pathway of complement
The lectin pathway is a type of cascade reaction in the complement system, similar in structure to the classical complement pathway, in that, after activation, it proceeds through the action of C4 and C2 to produce activated complement proteins further down the cascade. In contrast to the classical complement pathway, the lectin pathway does not recognize an antibody bound to its target.
Activation of the complement pathway through the classical, lectin or alternative complement pathway is followed by a cascade of reactions eventually leading to the membrane attack complex.

Ficolin

ficolin familyficolins
The lectin pathway starts with mannose-binding lectin (MBL) or ficolin binding to certain sugars.
Like collectins (Col+lectin) such as mannan-binding lectin, ficolins are secreted, lectin-type pattern recognition receptors, and similarly activate the lectin pathway of complement activation.

Complement system

complementcomplement cascadecomplement activation
The lectin pathway is a type of cascade reaction in the complement system, similar in structure to the classical complement pathway, in that, after activation, it proceeds through the action of C4 and C2 to produce activated complement proteins further down the cascade. Mannan-binding lectin, also called mannose-binding protein, is a protein belonging to the collectin family that is produced by the liver and can initiate the complement cascade by binding to pathogen surfaces.
Three biochemical pathways activate the complement system: the classical complement pathway, the alternative complement pathway, and the lectin pathway.

Lectin

lectinslectin protein lectin
In contrast to the classical complement pathway, the lectin pathway does not recognize an antibody bound to its target.

Mannan-binding lectin

mannose-binding lectinMBLMBL2
The lectin pathway starts with mannose-binding lectin (MBL) or ficolin binding to certain sugars.
Mannose-binding lectin (MBL), also called mannan-binding lectin or mannan-binding protein (MBP), is a lectin that is instrumental in innate immunity as an opsonin and via the lectin pathway.

Complement component 2

C2Complement component 2 deficiencyC2 deficiency
When the carbohydrate-recognising heads of MBL bind to specifically arranged mannose residues on the surface of a pathogen, MASP-1 and MASP-2 are activated to cleave complement components C4 and C2 into C4a, C4b, C2a, and C2b.
In the classical and lectin pathways of complement activation, formation of the C3-convertase and C5-convertases requires binding of C2 to an activated surface-bound C4b in the presence of Mg 2+ ; the resultant C4bC2 complex is then cleaved by C1s or MASP2 into C2a and C2b.

C3-convertase

C3 convertaseC3 convertasesclassical-complement-pathway C3/C5 convertase
If it is not then inactivated, it will combine with C2b to form the classical C3 convertase (C4bC2b) on the surface of the pathogen, as opposed to the alternative C3 convertase (C3bBb) involved in the alternative pathway.
C3 convertase formation can occur in three different pathways: the classical, lectin, and alternative pathways.

Map44

MBL-associated protein of 19 kDa (MAp19) and MBL-associated protein of 44 kDa (Map44).
MAp44 has been suggested to act as a competitive inhibitor of lectin pathway activation, by displacing MASP-2 from MBL, hence preventing cleavage of C4 and C2

MASP2 (protein)

MASP2MASP-2MASP2 deficiency
Multimers of MBL form a complex with MASP1 (Mannose-binding lectin-Associated Serine Protease), MASP2 and MASP3, that are protease zymogens.

Alternative complement pathway

alternative pathwayalternativealternate complement pathway

Cascade reaction

tandem reactiontandema series of reactions
The lectin pathway is a type of cascade reaction in the complement system, similar in structure to the classical complement pathway, in that, after activation, it proceeds through the action of C4 and C2 to produce activated complement proteins further down the cascade.

Mannose

mannose metabolismD-mannosemannosyl
In this pathway, mannose-binding lectin binds to mannose, glucose, or other sugars with 3- and 4-OH groups placed in the equatorial plane, in terminal positions on carbohydrate or glycoprotein components of microorganisms including bacteria such as Salmonella, Listeria, and Neisseria strains.

Glucose

dextroseD-glucose D -glucose
In this pathway, mannose-binding lectin binds to mannose, glucose, or other sugars with 3- and 4-OH groups placed in the equatorial plane, in terminal positions on carbohydrate or glycoprotein components of microorganisms including bacteria such as Salmonella, Listeria, and Neisseria strains.

Salmonella

Salmonella poisoningSalmonella typhibacteremic salmonellosis
In this pathway, mannose-binding lectin binds to mannose, glucose, or other sugars with 3- and 4-OH groups placed in the equatorial plane, in terminal positions on carbohydrate or glycoprotein components of microorganisms including bacteria such as Salmonella, Listeria, and Neisseria strains.

Listeria

Antilisterialmeningitis, listerialisteria infections
In this pathway, mannose-binding lectin binds to mannose, glucose, or other sugars with 3- and 4-OH groups placed in the equatorial plane, in terminal positions on carbohydrate or glycoprotein components of microorganisms including bacteria such as Salmonella, Listeria, and Neisseria strains.

Neisseria

Neisseria spp.Neisseria'' spp.
In this pathway, mannose-binding lectin binds to mannose, glucose, or other sugars with 3- and 4-OH groups placed in the equatorial plane, in terminal positions on carbohydrate or glycoprotein components of microorganisms including bacteria such as Salmonella, Listeria, and Neisseria strains.

Candida albicans

C. albicansCandidayeast
Fungal pathogens such as Candida albicans and Cryptococcus neoformans as well as some viruses such as HIV-1 and Respiratory syncytial virus (RSV) are bound by MBL.

Cryptococcus neoformans

C. neoformansCryptococcusCryptococcus (Filobasidiella) neoformans
Fungal pathogens such as Candida albicans and Cryptococcus neoformans as well as some viruses such as HIV-1 and Respiratory syncytial virus (RSV) are bound by MBL.

Subtypes of HIV

HIV-1HIV-2Human immunodeficiency virus 1
Fungal pathogens such as Candida albicans and Cryptococcus neoformans as well as some viruses such as HIV-1 and Respiratory syncytial virus (RSV) are bound by MBL.

Human orthopneumovirus

respiratory syncytial virushuman respiratory syncytial virusRSV
Fungal pathogens such as Candida albicans and Cryptococcus neoformans as well as some viruses such as HIV-1 and Respiratory syncytial virus (RSV) are bound by MBL.

Protein

proteinsproteinaceousstructural proteins
Mannan-binding lectin, also called mannose-binding protein, is a protein belonging to the collectin family that is produced by the liver and can initiate the complement cascade by binding to pathogen surfaces.

Collectin

COLEC12collectins
Mannan-binding lectin, also called mannose-binding protein, is a protein belonging to the collectin family that is produced by the liver and can initiate the complement cascade by binding to pathogen surfaces.

Liver

hepaticliver protein synthesislivers
Mannan-binding lectin, also called mannose-binding protein, is a protein belonging to the collectin family that is produced by the liver and can initiate the complement cascade by binding to pathogen surfaces.

Pathogen

pathogenspathogenicpathogenicity
Mannan-binding lectin, also called mannose-binding protein, is a protein belonging to the collectin family that is produced by the liver and can initiate the complement cascade by binding to pathogen surfaces.

Protease

proteasespeptidaseproteinase
Multimers of MBL form a complex with MASP1 (Mannose-binding lectin-Associated Serine Protease), MASP2 and MASP3, that are protease zymogens.