Human Body's Three Lines of Defense
By: Shawn Huang and Nikhil Padmanabhan
Second Line of Defense: Adaptative
The second line of defense consists of inflammatory responses and phagocytosis. The inflammatory responses include these four symptoms: redness, swelling, pain, and heat. Phagocytes such as macrophages and neutrophils search and destroy pathogens by engulfing them. This is a non-specific reaction because it doesn't require specific targeting.