What does factor H do in complement pathway?
Complement factor H is a soluble complement regulator essential for controlling the alternative pathway in blood and on cell surfaces. Normal recognition of self cell markers (i.e. polyanions) and C3b/C3d fragments is necessary for factor H function.
What is H factor blood?
Factor H is a soluble complementary glycoprotein present in the blood plasma that serves the primary function of controlling the alternative pathway in blood and maintaining homeostasis. In vitro experiments have also demonstrated factor H to have anti-thrombotic properties.
What is the function of Properdin?
Properdin is a positive regulator of complement activation that stabilizes the alternative pathway convertases (C3bBb). Properdin is composed of multiple identical protein subunits, with each subunit carrying a separate ligand-binding site.
What is factor H binding protein?
Factor H binding protein (fHbp) is a 27-kDa lipoprotein present on the surface of Neisseria meningitidis that improves the survival of the bacterium in human blood by binding human factor H (hfH), a down-regulator of the complement alternative pathway (1, 2).
What do Anaphylatoxins do?
The C3a, C4a and C5a components are referred to as anaphylatoxins: they cause smooth muscle contraction, vasodilation, histamine release from mast cells, and enhanced vascular permeability. They also mediate chemotaxis, inflammation, and generation of cytotoxic oxygen radicals.
What is complement deficiency?
Complement deficiency is a form of primary immunodeficiency disorder. Deficiency in any component of the complement system can lead to immunocompromise and overwhelming infection and sepsis. Deficiency can be inherited or acquired and complete or partial. Acquired deficiency can be caused by infection.
What is activation of complement?
Complement activation is a cascading event like the falling of a row of dominoes. It must follow a specific order if the end result is to be achieved. The circulating proteins have been grouped into three activation pathways, based on the types of substances and proteins that initiate the activation.
What is C3b and C5b?
The additional C3b molecule changes the specificity of the Bb so that it now prefers to cleave C5 into C5a and C5b. This enzyme is known as the alternative pathway C5 convertase. C5a is a potent proinflammatory peptide that diffuses away while C5b remains loosely bound to the C5 convertase C3bBb.
What is Properdin system?
The properdin system is responsible for the bactericidal action of normal human serum against a variety of microorganisms. The present work shows that the removal of properdin from serum also removes bactericidal activity. Addition of properdin to properdin-deficient serum restores bactericidal activity.
How many complement proteins are there?
The complement system refers to a series of >20 proteins, circulating in the blood and tissue fluids.