Macrophages In Inflammation

Macrophages In Inflammation

Question 1. Write a brief on the role of macrophages in inflammation.
Answer:

Following is the role of macrophages in inflammation:

• Phagocytosis (cell eating) and pinocytosis (cell drinking).
• Macrophages on activation by lymphokines released by T lymphocytes or by non-immunologic stimuli elaborate a variety of biologically active substances such as:
  • Proteases like collagenase and elastase degrade collagen and elastic tissue.
  • Plasminogen activator which activates the fibrinolytic system.
  • Products of complement.
  • Some coagulation factors convert fibrinogen to fibrin.
  • Chemotactic agents for other leucocytes.
  • Metabolites of arachidonic acid.
  • Growth-promoting factors for fibroblasts, blood vessels, and granulocytes.
  • Cytokines like interleukin-1 and tumor necrosis factor.
  • Oxygen-derived free radicals.

Macrophages in inflammation

Question 2. What is granuloma?
Answer:

Granuloma is defined as a circumscribed tiny lesion about 1 mm in diameter composed predominantly of a collection of modified macrophages known as epithelioid cells and rimmed at the periphery by lymphoid cells.

Question 3. Write briefly on complications of wound healing.
Answer:

The following are the complications of wound healing:

Role of macrophages in chronic inflammation

1. Wound infection due to bacteria causes delayed healing
2. Formation of implantation cyst because of the persistence of epithelial cells in the wound after healing.
3. Pigmentation: Healed wounds have rust-like color due to hemosiderin pigmentation. If some colored material is left inside the wound it can persist and provide color to the wound.
4. Deficient scar formation: It can occur due to inadequate formation of granulation tissue.
5. Incisional hernia: Weak scar after laparotomy can be the site of the bursting open of a wound.
6. Hypertrophied scar and keloid formation: Sometimes the scar formed is ugly, excessive, and painful. Excessive formation of collagen in healing may result in the formation of keloid. Hypertrophied scars are confined to the border of the wound while keloids are tumor-like projections of connective tissue.
7. Excessive contraction: Exaggeration of wound contraction leads to the formation of contractures or cicatrization.
8. Neoplasia: It is very rare that a scar may be the site for the development of carcinoma later.