The classical pathway of complement activation is initiated when the C1 complex, made up of C1r and C1s serine proteases, recognizes the Fc region of IgM or IgG antibodies bound to a pathogen. (wikipedia.org)
C1q mediates the classical pathway by activating the C1 complex, which cleaves C4 and C2 into smaller fragments (C4a, C4b, C2a, and C2b). (wikipedia.org)
Bind3
The lectin pathway is activated when pattern-recognition receptors, like mannan-binding lectin or ficolins, recognize and bind to pathogen-associated molecular patterns on the antigen, including sugars. (wikipedia.org)
This activation induces a conformational change in the thioester domain of C3(H2O) that allows it to bind to a plasma protein called Factor B. This complex is then cleaved by Factor D, a serine protease, to form C3b(H2O)Bb, or fluid-phase C3-convertase. (wikipedia.org)
or actively by prior immunization of the recipient with graft antigens which evoke specific antibodies and form antigen-antibody complexes which bind to the antigen receptor sites of the T-cells and block their cytotoxic activity. (lookformedical.com)
Proteins3
The reason for this is that these proteins help to clean up large groups of molecules called immune complexes before they can cause inflammation. (mastattack.org)
Without these proteins, immune complexes and dead cells are not removed and cause local irritation. (mastattack.org)
In HAE types I and II, complement proteins C2 and C4 are low. (mastattack.org)
Inflammation4
In this review we discuss current evidence that complement activation contributes to progression of CKD, how complement could cause renal inflammation and whether complement inhibition would slow progression of renal disease. (wjgnet.com)
Complement activation occurs in progressive chronic kidney disease and may contribute to the chronic inflammation that is characteristically found in the kidney. (wjgnet.com)
It is therefore possible that inhibiting complement activation would reduce inflammation, lead to reduced fibrosis and preservation of renal function. (wjgnet.com)
Pathogenic mechanisms of bradykinin mediated diseases: dysregulation of an innate inflammation pathway. (mastattack.org)
Immune3
The complement system is an integral part of the innate immune system but also augments adaptive immune responses. (wjgnet.com)
However, HAE patients have been shown to have a normal level of immune complexes. (mastattack.org)
An immune response with both cellular and humoral components, directed against an allogeneic transplant, whose tissue antigens are not compatible with those of the recipient. (lookformedical.com)
Rejection2
Complement activation is known to occur in many diverse renal diseases, including glomerulonephritis, thrombotic microangiopathies and transplant rejection. (wjgnet.com)
Donor and recipient pairs should be of identical ABO blood group, and in addition should be matched as closely as possible for HISTOCOMPATIBILITY ANTIGENS in order to minimize the likelihood of allograft rejection. (lookformedical.com)
Occurs1
C3a formation occurs through activation and cleavage of complement component 3 in a reaction catalyzed by C3-convertase. (wikipedia.org)
Form1
The alternative pathway of complement activation is typically always active at low levels in blood plasma through a process called tick-over, in which C3 spontaneously hydrolyzes into its active form, C3(H2O). (wikipedia.org)
System1
C3a is an effector of the complement system with a range of functions including T cell activation and survival, angiogenesis stimulation, chemotaxis, mast cell degranulation, and macrophage activation. (wikipedia.org)
Activation1
There are three pathways of activation, each of which leads to the formation of C3a and C3b, which is involved in antigen opsonization. (wikipedia.org)
Alternative2
Other than the alternative pathway, which is constantly active, C3a formation is triggered by pathogenic infection. (wikipedia.org)
Antigens that exist in alternative (allelic) forms in a single species. (lookformedical.com)
Component2
C3a has a regulatory process and a structure homologous to complement component C5a, with which it shares 36% of its sequence identity. (wikipedia.org)
Deficiencies of an early component of the classical complement pathway (C1q, C1r, C1s, C2, C4) have been associated with lupus like autoimmune conditions. (mastattack.org)
Plasma1
The plasma bradykinin-forming pathways and its interrelationships with complement. (mastattack.org)