Mediators of Acute Inflammation

Introduction

Acute inflammation is a rapid immune response to injury or infection, characterized by redness, swelling, heat, and pain. It is a critical defense mechanism that helps the body eliminate harmful stimuli and begin tissue repair.

Key Mediators of Acute Inflammation

Chemical Mediators

• Histamine - Released by mast cells, histamine increases vascular permeability and causes vasodilation.
• Prostaglandins - Derived from arachidonic acid, they contribute to fever, pain, and vascular changes.
• Leukotrienes - Also derived from arachidonic acid, leukotrienes recruit immune cells and enhance inflammation.
• Cytokines - Signaling proteins such as TNF-α and IL-1 regulate immune response and inflammation.

Cellular Mediators

• Neutrophils - First responders that phagocytose pathogens and release enzymes.
• Macrophages - Play a role in antigen presentation and cytokine secretion.

Stages of Acute Inflammation

1. Initiation - Detection of harmful stimuli and activation of immune cells.
2. Amplification - Mediators increase vascular permeability, attracting immune cells.
3. Resolution - Anti-inflammatory mechanisms restore tissue homeostasis.