KEY CONCEPT When the immune system is weakened, the body cannot fight off disease.

Leukemia is characterized by abnormal white blood cells. Leukemia is cancer of the bone marrow. characterized by immature white blood cells They are immature so they cannot fight pathogens causes weakened immune system

Leukemia leads to opportunistic infections. occur because white blood cells cannot fight infections if immune system were healthy, would fight these infections

Only cure- is a bone marrow transplant (Patient must undergo chemo and radiation = kill both cancer and healthy cells)

HIV targets the immune system. The human immunodeficiency virus (HIV) is a retrovirus (uses your body to duplicate its DNA) attacks and weakens the immune system is transmitted by mixing infected blood or other bodily fluids

HIV infection leads to AIDS. T cell dead T cell antibody activated B cell HIV reproduces in and destroys T cells. The body cannot replace T cells fast enough. T cells cannot help in immune responses.

Ways to get HIV Sexual intercourse (semen/vaginal fluid) Mother to child (umbilical cord and/or breast milk) Blood to blood contact (sharing needles/blood transfusion)

AIDS is acquired immune deficiency syndrome. Final stage of immune system decline Due to HIV several opportunistic infections Pneumonia Viral infections Cancers tuberculosis Immune system is worn out very low amount of T cells Medicine slows, but does not cure ALWAYS results in death