Wikipedia
Physical effects resulting from activation of the immune system
Summary
Inflammation is part of the biological defence response of body tissues. Inflammatory immunovascular responses can be triggered by a broad range of stimuli, including physical trauma, “dead, damaged, malfunctioning or stressed tissues”, pathogens, irritants, toxins, overuse, autoimmunity, allergens, and foreign bodies. The five cardinal signs are heat, pain, redness, swelling, and loss of function.