Acute-phase reactants

Question 1

What are positive (upregulated) acute-phase reactants?

Answer 1

C-reactive protein

• opsonin
• fixes complex
• facilitates phagocytosis
• measured clinically as nonspecific sign of ongoing inflammation

Ferritin
- binds & sequesters iron to inhibit microbial iron scavenging

Fibrinogen

• coagulation factor
• promotes endothelial repair
• correlates with ESR

Hepcidin

• ↓ iron absorption (by degrading ferroportin)
• ↓ iron release (from macrophages) → anemia of chronic disease

Haptoglobin

• binds haemoglobin (thus preventing iron loss and renal damage)
• antioxidant/ antibacterial/ acute-phase response modulator

Serum amyloid A

• cytokine synthesis
• prolonged elevation can lead to amyloidosis

Question 2

What are negative (downregulated) acute-phase reactants?

Answer 2

Albumin
- reduction conserves amino acids for +ive acute-phase reactants

Transferrin
- internalized by macrophages to sequester iron

Question 3

What cytokine most notably induces acute-phase reactants?

Answer 3

IL-6

Question 4

Which acute-phase reactant binds & sequesters iron to inhibit microbial iron scavenging?

Answer 4

Ferritin

Question 5

Which acute-phase reactant ↓ iron absorption (by degrading ferroportin) & ↓ iron release (from macrophages)?

Answer 5

Hepcidin