What clinical condition is associated with Properdin deficiency?
All three variants of properdin deficiency are clinically characterized by a significant risk of meningococcal disease, particularly in association with unusual infective serotypes such as W-135 and Y [15,16].
Where does properdin come from?
Neutrophils are the major source of properdin. Monocytes, bone marrow progenitor cell lines and T cells also produce properdin (Wirthmueller et al., 1997). Human monocytes have been shown to secrete alternative pathway complement proteins including properdin (Whaley, 1980).
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 does the alternative complement pathway start?
The alternative pathway is one of three complement pathways that opsonize and kill pathogens. The pathway is triggered when the C3b protein directly binds a microbe. It can also be triggered by foreign materials and damaged tissues.
What is the most severe complement deficiency?
C2 deficiency is the most common complement deficiency, with frequency estimates between 1 in 10,000 to 1 in 20,000 for homozygous C2-deficient patients. C2 deficiency is found in a slightly higher proportion of SLE patients compared to healthy controls.
What are some common complications associated with a deficiency in the complement system?
Complement deficiency 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. MBL deficiency is thought to be the most common.
What is the role of Properdin in the complement cascade?
Properdin is known as the only positive regulator of the complement system. Properdin promotes the activity of this defense system by stabilizing its key enzymatic complexes: the complement alternative pathway (AP) convertases.
Which pathway is known as Properdin pathway?
The properdin complement pathway is initiated as a result of spontaneous hydrolysis of the C3 component of complement in serum. This produces a cleavage product, C3b, that binds to microbial surfaces, forming an enzyme, C3 convertase, which initiates the activation of the subsequent complement components (Figure 12.1).
What is needed to activate Properdin?
What are the 3 ways the alternative complement pathway can be triggered?
The alternative pathway is one of three complement pathways that opsonize and kill pathogens. This pathway is activated by viruses, fungi, bacteria, parasites, cobra venom, immunoglobulin A, and polysaccharides and forms an important part of the defense mechanism independent of the immune response.
What activates complement alternative?
The alternative complement pathway can be activated as a by-product of the classic pathway when the C4–C2 dimer facilitates direct binding of the activated C3 to the pathogen surface as above or when circulating C3 is spontaneously hydrolyzed and acted on by two proteins (factors B and D) to form a free C3 convertase …
What is the main function of the serum protein Properdin in complement system?
Properdin is plasma glycoprotein that activates the complement system of the innate immune system. This protein binds to bacterial cell walls and dying human cells to stabilize the C3 and C5-convertase enzyme complexes to form an attack complex that lead to the lysis of the cell.
What is the role of properdin in the complement cascade?
Which of the following complement pathways employs properdin?
Which of the complement pathways employs properdin? d. Alternative and lectin pathways all employ properdin.
Can all 3 complement pathways be activated at the same time?
Complement can be activated via three different pathways (Figure 1), which can each cause the activation of C3, cleaving it into a large fragment, C3b, that acts as an opsonin, and a small fragment C3a (anaphylatoxin) that promotes inflammation.
What complement deficiency is fatal and can cause overwhelming infection?
C3 deficiency There may be a deficiency of C3 itself or a deficiency of other complement components in the classic, alternative or MBL pathways (ie above C3 in the cascade). Primary C3 deficiency tends to present in early life with overwhelming infection with encapsulated organisms.