The immune system is a complex network of tissues, organs, cells, and chemicals that protects the body from infection and illness. The lymph nodes, spleen, bone marrow, thymus gland, and tonsils all play a role, as do white blood cells, antibodies, and interferon.

Two types of immunity protect the body - innate and adaptive. Innate immunity given to us by birth, provides the first barrier against microorganisms. The skin, mucus secretions, and the acidity of the stomach are examples of innate immunity.

Adaptive immunity is the second barrier to infection. It is acquired later in life, such as after an immunization or successfully fighting off an infection. The adaptive immune system retains a memory of all the invaders it has faced.

Simply put the immune system is like a team. This team is comprised of many different cells that work together to keep you healthy. They all have specialized functions and ways of communicating with each other. The two important tasks of the immune system are to kill pathogens and to remember.

All pathogens release certain chemicals and proteins that our immune defense recognizes. Recognition triggers a kill response.  When an invader returns, the team members responsible for remembering past invasions sense the invader’s chemical signals that stimulates them to produce chemical tags called antibodies. These antibodies stick to the invaders and enable killer cells to recognize and kill again.