complement Flashcards
What is the role of the membrane attack complex (MAC)?
The MAC defends against gram-negative bacteria by causing cytolysis of the target cell.
What test is used to screen for activation of the classical complement pathway?
The CH50 test is used to screen for activation of the classical complement pathway.
Which immunoglobulins mediate the classical complement pathway?
The classical complement pathway is mediated by IgG and IgM.
What triggers the alternative complement pathway?
also called the spontaneous pathway , where 3b binds to amino and hydroxyl groupsThe alternative pathway is triggered by microbe surface molecules.
What triggers the lectin complement pathway?
The lectin pathway is triggered by mannose or other sugars on the surface of microbes.
What are the functions of C3b?
C3b functions as an opsonin to enhance phagocytosis and also helps clear immune complexes.
What are the roles of C3a, C4a, and C5a?
C3a, C4a, and C5a are involved in anaphylaxis, and C5a specifically plays a role in neutrophil chemotaxis.
Which components form the MAC?
The MAC is formed by components C5b through C9.
What are the primary opsonins in bacterial defense?
The primary opsonins are C3b and IgG.
How does C3b bind to bacteria?
C3b binds to lipopolysaccharides on the surface of bacteria.
Why is the MAC particularly important for Neisseria species?
The MAC is critical for neutralizing Neisseria species. Its deficiency results in recurrent infections.
What inhibitors prevent complement activation on self cells?
Decay-accelerating factor (DAF, also called CD55) and C1 esterase inhibitor prevent complement activation on self cells such as red blood cells.
as well as the H factor
What mnemonic can help you remember the classical pathway?
“General Motors makes classic cars” helps remember the classical pathway.
What mnemonic can help you recall the MAC components’ importance for Neisseria?
“Get ‘Neis’ (nice) Big MACs from 5-9 pm” helps recall that the MAC (C5b-9) is important for Neisseria.
where are the amino and hydroxyl groups used for the alternative pathway found ?
LPS
fungal cell walls
viral envlopes
what is the lectin pathway ?
it is the third pathway for complement activation where it is activated by mannose , once its bound MASPS are activated
which then claves C2 and C4 into C2b and C4b which fuse together to form C2b4b which. is C3 convertase
whats common betweeen the lectin pathway and the classcical pathway ?
they both use C2b4b too make C3 convertase
what is the function of IL 6 ?
stimulates the liver for the formation of CRP
activates classical pathway via C1 binding
which complement are anaphyltoxins ?
C3a and C5a
what type of bacteria is mainly affected by complement ?
encapsulated
why does paroxysmal nocturnal hemoglobinura ?
due to a deficiency in DAF/CD95
what is the presentation off paroxysmal nocturnal hemoglobinuria ?
sudden hemolysis att nnight
thrombosis
priapism
dysphagia
abdominal pain
low haptglobin and dark urine
what is the presentation of recurrent C3 deficiency ?
recurrent infections of encapsulated bacteria
pneumococcal and h influenza
GN
type 3 hypersensitivity syndrome
what is the presentation of C5 to C9 deficiency ?
recurrent niesseria infection, most oftn presents as meningitis
what is the presentation of C1 inhibitor deficiency ?
hereditary angioedema
without urticaria
what specific must always be avoided with hereditary angioedema?
ACE inhibitor
what diseases are associated with low complement levels ?
lupus
MPN
post strep GN
which complement is sed in thee clearance of antigen antibody complexes ?
C3b
terminal compliment deficiencies ?
higher risk of neisseria
what gene mutation is associated with paroxysmal nocturnal hemoglobinuria ?
PIGA
function of
C3b
C3a, C4a, C5a
C5a
5b-9
opsonization
anaphyltoxin
neutrophil chemotaxis
MAC
