9-5 Complement System Flashcards
Complement Activation = OIL
Opsonization
Inflammation
Lysis
Opsonization
Complement activation acts like a glue to attach substances or antibodies to invading organisms to help phagocytosis by PMNs/macrophages
Inflammation
Complement activation induces acute inflammation to dilate blood vessels by activating mast cells/basophils and to recruit inflammatory phagocytic cells to eat invading organism
Lysis
Complement activation generates a group of proteins able to penetrate the invading organism’s cell wall to induce lysis
Classical pathway starting point
- C1qrs, C2, C4
- triggered by antibody so it is part of the adaptive immune system
Alternative pathway starting point
- C3, factor B, D and properdin
- part of the innate immune system
Lectin pathway starting point
- plasma derived mannose binding lectin (MBL)
- part of the innate immune system
Common goal of the three pathways
Deposit C3b (opsonins) on target (opsonization)
Anaphylatoxins
- C3a, C4a, C5a
- increase vascular permeability
Chemoattractants
- C3a, C5a
- attract neutrophils and monocytes
Microbes with C3b attached are phagocytosed because it is recognized by _____
complement receptor type 1 (CR1)
C3 deficiency
profound risk of encapsulated bacteria infection
C5b, C6, C7, C8, C9 deficiency
increased susceptibility to Neisseria infections (especially susceptible to membrane attack complex which can’t form)
C1, C2, C4 deficiency
increased risk of immune complex disease, SLE
C1-inhibitor deficiency
excess of vasoactive peptides (bradykinin) generated -> edema
