Complement Flashcards
What do C3a and C5a do?
- Recruit phagocytic cells to the site of infection
2. Promote inflammation
What receptor RBCs binds the immune complex via C3b? Where do the RBCs bring the immune complex?
CR1
To the spleen and liver where phagocytic cells remove the immune complex from the RBC surface (bind with FcR)
What is an important chemoattractant? What does it attract?
C5a recruits neutrophils, eosinophils, basophils, and monocytes
What causes vascular changes at the sight of complement?
C3a, C4a, C5a are capable of binding specific receptors on mast cells and basophils triggering granule release
-release of histamine leads to vascular changes–>increased vascular permeability
C3a, C4a, C5a are also called anaphylatoxins
What inhibits C1?
C1 INH- inhibits C1 by dissociating C1r and C1s from the C1 complex
WHat inhibits C3 convertase?
Decay-accelerating factor--DAF C4 Binding Protein---C4BP Complement receptor 1--CR 1 membrane cofactor protein--MCP Factor I
What inhibits C5 convertase?
Factor I, Factor H, CR 1
What prevents assembly of MAC?
CD59
What do deficiencies of classical pathway lead to?
Immune complex disease
What do deficiencies of lectin pathway lead to?
bacterial infections, mainly in early childhood
What do deficiencies in alternative pathway lead to?
infection with pyogenic bacteria and Neisseria spp.
-no immune complex disesase
What does C3b deficiency lead to?
infection with pyogenic bacteria and Neisseria spp.
-sometimes immune complex disesase
What do deficiencies in C5, 6,7,8,9 lead to?
infection with Neisseria spp. only
What does hereditary deficiency of C1 inhibitor (C1 INH) lead to?
-hereditary angioneurotic edema
Clinical Symptoms
-swelling, abdominal attacks, edema of upper airway, epiglottal swelling
Treatment
acute attacks- C1-INH concentrate
What is paroxysmal nocturnal hemoglobinurea?
CD59 failure
- lack of complement regulation
- leads to RBC lysis
