It is a fatal disease caused by a virus, a tiny organism similar to those that cause colds and flu. HIV infection causes people to get AIDS by damaging their immune systems. Your immune system is what defends you against the many different organisms that can enter the body and cause sickness. Without the ability to resist disease, people with AIDS fall ill easily, get sick often, and have great difficulty recovering. People do not die from HIV infection directly.
Human blood is essential to the body's immune system.
It is made up of many small cells that help your body work properly, and among those cells are several types of white cells that protect you from disease. The B cells produce antibodies which destroy harmful organisms that invade the body. T cells help regulate the production of antibodies by the B cells. There are two types of T cells - helper cells and suppressor cells. Helper cells help produce antibodies and suppressor cells stop or suppress the production of antibodies.