Innate immunity: the immediate response to infection

Question 1

Immediate response components

Answer 1

Complement, cytokines, anti-microbial peptides.

Question 2

Most important component of complement

Answer 2

C3b, get’s attached to particles, opsonizing them

Question 3

C3a

Answer 3

Chemotactic, recruits other immune cells

Question 4

How are C3b attached?

Answer 4

Covalently

Question 5

Spontanous activation of C3

Answer 5

C3 sponatanously becomes iC3, get’s attached to B, that gets cleaved by D, creating iC3Bb. iC3Bb is a C3bBb convertase

Question 6

Alternative pathway amiplification

Answer 6

Fixed C3b cleaves and activates more C3, producing more C3b and C3a

Question 7

MAC attack

Answer 7

C3b2Bb cleaves C5, causing subsequent activation of C6, 7, 8 and 9. Forming membrane pore.

Question 8

Anaphylatoxin

Answer 8

C3a and C5a increases vascular permeability and recruits immune cells.

Question 9

Decay acceleration factor

Answer 9

Binds C3bBb and causes dissociation of Bb. Important for self-tolerance.

Question 10

Lectin pathway

Answer 10

Lectin (MBL) bound MASP-1 and 2 binds to mannose on bacteria. MASPs can cleave C4 to C4b, allowing association with C2a. C4b2a is is a C3bBb convertase.

Question 11

Classical pathway

Answer 11

C1 complex binds IgM or CRP. C1 generates C4b2a, generating C3bBb.

Question 12

Therapeutic targeting of C5

Answer 12

Can treat paroxysmal nocturnal hemoglobinurea

Question 13

Defensins

Answer 13

Const. secreted antimicrobials. Secreteds as pro-defensin. Defensin inserts itself in the membrane, causing pore formation.