Immune cells refer to a group in the human body specialized in "defense." Commonly known as white blood cells, immune cells include various lymphocytes and phagocytes that can recognize and eliminate antigens, participating in immune responses. Our body is akin to an independent country, and the immune system serves as our military and police force. It not only acts as the military to identify and eliminate invading pathogens but also functions as the police to recognize and eliminate mutated, dying cells, or other harmful substances within the body.