Question of the Day

Acquired Immune Deficiency Syndrome (AIDS) is caused by the human immunodeficiency virus (HIV). HIV infects and kills helper T cells, which play an important role in cellular- and antibody-based responses of the body’s immune system to foreign substances. The majority of the systemic effects of HIV-infection can be attributed to the loss of these helper T cells, also known as CD4 cells. This loss suppresses the ability of other important components of the immune system to protect the body from infections that are normally not dangerous to individuals who are not immunocompromised. These other cells include killer T cells, which destroy infected and otherwise abnormal cells within the body, as well as plasma cells, which produce antibodies that interact with and neutralize foreign substances. Finally, although anemia (abnormally low levels of red blood cells, or erythrocytes) is a common observation in patients with AIDS, this is only an indirect consequence of the effects of HIV on the immune system. The HIV virus cannot infect and replicate in red blood cells, which lack nuclei and other features necessary for HIV infection.