Overview of Interferons

Type I Interferons

Interferon Alpha (IFN-α)

• Mainly Secreted By:
  • Virus-infected cells and malignant cells
  • Fibroblasts (interferon-β)
• Function:
  • Acts as the first line of defense against all viral infections
  • Inhibits viral protein synthesis by activating ribonuclease L, leading to the degradation of cellular and viral mRNA
  • Promotes the expression of MHC class I molecules, aiding in the recognition of virus-infected cells and activation of NK cells and cytotoxic T cells
  • Inhibits megakaryocyte stem cell differentiation and proliferation
• Therapeutic Use:
  • Chronic hepatitis B
  • Acute and chronic hepatitis C
  • Kaposi sarcoma
  • Adjuvant therapy for malignant melanoma
  • Renal cell carcinoma
  • Condyloma acuminatum
  • Hairy cell leukemia
  • Essential thrombocythemia
• Side Effects:
  • Flu-like symptoms (fever, chills)
  • Depression
  • Myopathy
  • Neutropenia
  • Interferon-induced autoimmunity
  • Gastrointestinal issues (nausea, vomiting, diarrhea)
  • Itchy skin

Interferon Beta (IFN-β)

• Therapeutic Use:
  • Multiple sclerosis

Type II Interferons

Interferon Gamma (IFN-γ)

• Mainly Secreted By:
  • Th1 and NK cells (when stimulated by IL-12 from macrophages or antigen contact)
• Function:
  • Activates macrophages to increase phagocytosis (positive reinforcement) and NK cells to eliminate virus-infected target cells
  • Synergistic effect with tumor necrosis factor in stimulating macrophages to form granulomas, crucial against mycobacterial infections
  • Suppresses a Th2 response (negative feedback)
  • Promotes the expression of MHC class II molecules and antigen presentation in every cell
  • Stimulates antigen class switching to IgG3
• Therapeutic Use:
  • Chronic granulomatous diseases (e.g., leprosy, leishmaniasis, toxoplasmosis)