The autoimmune system keeps the body healthy by protecting it against organisms, such as bacteria and viruses that can cause infections. The immune system can destroy many of these different types of invading microorganisms, states the University of Chicago Medicine. The immune system consists of different cells, tissues and organs that work in unison to defend the body against infectious pathogens.
White blood cells are called leukocytes, but there are two different types of leukocytes that are phagocytes and lymphocytes, notes KidsHealth. Each of these types of white cells performs different functions in the body. The main function of neutrophils, which are types of phagocytes, is to respond and defend the body against bacterial infections.
Lymphoid organs found in different parts of the body produce and release lymphocytes that travel throughout the body through either blood or lymphatic vessels. Some lymphoid organs are bone marrow, lymph nodes, thymus and spleen, according to the University of Chicago Medicine. There are different types of lymphocytes, including B and T lymphocyte cells that have different functions. B cells work by making antibodies that target a particular antigen or foreign agent while T cells kill organisms in body cells that are affected by these invaders.
The immune system provides two types of defense, which are innate and acquired immunity. Innate immunity is termed the first line of defense, and it is the physical barriers of the body, such as skin, mucus membranes that prevent pathogens from penetrating the body. Antibodies are also part of innate immunity. Acquired immunity occurs when the body builds up immunity through exposure to certain infections or vaccination, states MedicineNet.