The immune system is the collection of cells, tissues, and molecules that work together to recognize the healthy cells that make up the body, and protect us against the unfamiliar or damaged.
The immune system monitors our body continuously searching for certain categories of things that may threaten our health: infectious microbes, viruses, fungi, and parasites (i.e., germs or pathogens); toxic cellular products; and damaged or diseased cells, including senescent or tumor cells.
