The terms "tumor, rubor, calor, and dolor" originate from ancient Roman physician Galen and are still relevant in modern medicine. They describe the cardinal signs of inflammation: swelling, redness, heat, and pain. "Functio laesa" refers to impaired tissue function during inflammation, emphasizing that it involves more than just visible symptoms.

The inflammatory response involves three phases: initiation, effector mechanisms, and resolution. Initiation includes pathogen or damage recognition and activation of inflammatory mediators. Effector mechanisms involve vasodilation, immune cell recruitment, and phagocytosis. Finally, resolution includes anti-inflammatory signals, tissue repair, and return to homeostasis.

Pathogens deploy diverse evasion tactics against the human innate immune system, including mimicry, inhibition of signaling pathways, and resistance to immune cell actions. Through mechanisms like antigenic variation and interference with inflammasome activation, pathogens constantly challenge the immune response. Understanding these strategies is vital for enhancing immune defense and developing effective therapeutic interventions.