Here are some common examples of immune system disorders: 1.Severe combined immunodeficiency (SCID). This is an example of an immune deficiency that is present at birth. Children are in constant danger of infections from bacteria, viruses, and fungi. This disorder is sometimes called “bubble boy disease.” In the 1970s, a boy had to live in a sterile environment inside a plastic bubble. Children with SCID are missing important white blood cells. 2.Temporary acquired immune deficiencies. Your immune system can be weakened by certain medicines, for example. This can happen to people on chemotherapy or other drugs used to treat cancer. It can also happen to people following organ transplants who take medicine to prevent organ rejection. Also, infections like the flu virus, mono (mononucleosis), and measles can weaken the immune system for a brief time. Your immune system can also be weakened by smoking, alcohol, and poor nutrition. 3.AIDS. HIV, which causes AIDS, is an acquired viral infection that destroys important white blood cells and weakens the immune system. People with HIV/AIDS become seriously ill with infections that most people can fight off. These infections are called “opportunistic infections” because they take advantage of weak immune systems.
There are two types of adaptive immune responses: humoral immunity, mediated by antibodies produced by B lymphocytes, and cell-mediated immunity, mediated by T lymphocytes. The illustration below is divided into the main components of the innate and adaptive immune systems