04 Complement

• great for encapsulated bacteria

C3

• Overview of complement
• 3 different pathways, next step always MAC

Alternative Pathway

• destroyed in less than a second if not bound

C3b

• stable c3b creates more of itself via positive loop

Factor H

Lectin Pathway

Classical pathway

• Alternative and MBL part of innate immunity

C1

• IgM: 2 Fc very close together, easy C1 binding
• IgG: ok complement activation

CRP

• binds C polysaccharides of bacteria

C3a C3b

MAC

• aka late complement

C5a

Inhibition

PNH

• DAF/CD59 deficiency
• start at RBC lysis
• Free plasma Hgb thrombogenic
• Priapism: sustained prolonged erection

C3 Deficiency

• immune complex: antigen-antibody, usually cleared via complement binding and macrophage

C5-9 deficiency

• not as bad as c3 deficient

Hereditary Angioedema

• c1 inhibitor breaks down bradykinin

• urticaria: histamine, not here
• Epinephrine doesn't work

• ace inhibitor block bradykinin breakdown

  C3 Nephritic

Hypocomplementemia

• CH50: classic pathway lysis sheep RBC. Qualitative test, yes or no