Select all the cardinal signs of inflammation. Select all that apply

Inflammation is the body’s protective response to injury, infection, or irritation. It aims to remove harmful stimuli, initiate tissue repair, and restore homeostasis. Clinically, inflammation is identified by a set of classic physical signs, first described in ancient Roman medicine, which indicate localized vascular and immune system activity in the affected area.

Rationale for correct answers:

1. Tumor: Refers to swelling, which occurs due to fluid accumulation and increased vascular permeability in the inflamed tissue.

3. Calor: Heat develops as a result of increased blood flow (hyperemia) to the inflamed area.

4. Rubor: Redness results from vasodilation and increased perfusion to the site of injury or infection.

5. Dolor: Pain occurs when chemical mediators such as bradykinin and prostaglandins stimulate sensory nerve endings.

Rationale for incorrect answer:
2. Palor: Paleness is not a feature of inflammation; in fact, inflammation typically causes redness (rubor), making palor the opposite of what is expected.

Take home points:

• The classic cardinal signs of inflammation are Rubor (redness), Calor (heat), Tumor (swelling), Dolor (pain), and sometimes Functio laesa (loss of function).
• These signs were first described by the Roman physician Celsus and remain key indicators of inflammation in modern medicine.

Secreting growth factors that stimulate angiogenesis and collagen synthesis is the primary role of macrophages during the proliferative phase. In this phase, macrophages shift from primarily phagocytic activity (in the inflammatory phase) to a reparative role, releasing cytokines and growth factors such as VEGF and TGF-β, which promote new blood vessel formation and stimulate fibroblasts to produce collagen for tissue repair.

Rationale for correct answer:
3. Secreting growth factors: Macrophages act as key regulators of wound healing by promoting angiogenesis, fibroblast proliferation, and extracellular matrix production, all critical for granulation tissue formation.

Rationale for incorrect answers:

1. Initiating vasoconstriction: This is the role of platelets and vascular smooth muscle during the hemostasis phase, not the proliferative phase.

2. Phagocytizing bacteria and debris: This is the main macrophage role in the inflammatory phase, though some clearance may continue early in the proliferative stage.

4. Producing histamine: Histamine release comes mainly from mast cells and basophils during the early inflammatory response, not from macrophages in the proliferative phase.

Take home points:

• The proliferative phase focuses on tissue rebuilding, not just inflammation control.
• Macrophages transition from “clean-up crew” to “construction managers,” directing fibroblasts and endothelial cells.
• Growth factors from macrophages are essential for angiogenesis, collagen deposition, and granulation tissue formation.