Immunology is a branch of biology and medical science that studies the immune system. Immunology is important because understanding how the body defends itself from infection helps scientists create more effective treatments for disease as well as vaccines that prevent illness.

When your body can resist infection from a particular virus or bacteria, you are considered immune. Once you are exposed — by natural infection or vaccine — your immune cells defend you by creating proteins called antibodies, which fight the infection. Afterward, your immune cells will remember that source of infection; if you are exposed to it again, these cells will recognize it and fight it off before it causes illness.

Immunotherapy is a class of treatments that activate or enhance the immune system so that it resists a target disease more effectively. So far, it’s been used to fight cancer, but in the future it may be applied to other diseases as well. One example is monoclonal antibody therapy, which gives patients antibodies that are lab-engineered to attack specific proteins on cancer cells. Another example is CAR T cell therapy, where white blood cells called T cells are taken from the patient, engineered to recognize and attack cancer cells, and then put back in the patient’s body.

It’s been well established that cancers create proteins that the immune system can recognize. The Biodesign Center for Innovations in Medicine is currently exploring a vaccine target for breast cancer. If we could vaccinate an individual with a collection of proteins that a breast tumor might produce, the immune system would arm itself against breast cancer. If this platform technology proves successful, it could be applied to other cancers.

The immune system exists throughout the whole body and involves many different parts working together. Most immune cells grow from stem cells made in bone marrow. There are many kinds of immune cells, like killer T cells that destroy infected cells, B cells that can become plasma cells, plasma cells that make proteins called antibodies, and helper T cells that aid other T cells and B cells. These cells circulate through the bloodstream and the lymphatic system, where they patrol for infection. Organs such as the spleen, thymus and tonsils are important hubs where your body stores, matures or uses immune cells. Mucous membranes like those found in the respiratory and digestive tracts trap germs and destroy them with enzymes. The intestines also harbor good bacteria that fight bad bacteria.