ABO blood group:

The major human blood type determined by the presence or absence of two antigenic structures, A and B, on red blood cells, consisting of four blood types (A, B, AB, and O).

Acquired immunodeficiency syndrome (AIDS):

An acquired, as opposed to inherited (congenital), disease characterized by the progressive deterioration of host immune defenses that renders the affected individual susceptible to an array of infectious and malignant disorders that do not normally afflict persons with intact immune systems. AIDS results from infection with human immunodeficiency virus (either type 1 or type 2), and is formally defined by a case definition issued by the Centers for Disease Control and Prevention (CDC).

Active immunity:

Protection against an infectious disease that results from induction of host immune defense mechanisms including antibodies (humoral immunity) and cytotoxic T-lymphocytes (cellular immunity). These host immune effectors are specifically induced by exposure to constituents of the infectious pathogen as a result of prior infection or immunization (compare with "passive immunity").

AIDS-related complex (ARC):

A term formally used to describe the various signs and symptoms including lymphadenopathy, unexplained fevers, weight loss, and specific infections that characterized the early stages of AIDS. Initially it was not known whether ARC represented a prodrome to full-blown AIDS or a separate, less severe, form of the disease. With the recognition that persons who manifest these early signs and symptoms will ultimately progress to AIDS, HIV-associated disease is now recognized as a continuum spanning asymptomatic infection, mild to moderate symptomatology and, ultimately, the profound immunodeficiency of AIDS.

AIDS-related retrovirus (ARV):

A retrovirus isolated from an individual with AIDS by Dr. Jay Levy's laboratory at the University of California, San Francisco. Subsequent studies demonstrated that ARV is a representative of the HIV-1 group of retroviruses.


A small protein, synthesized in the liver, which is the principal protein in plasma and is important in maintaining plasma volume through maintenance of an osmotic gradient between plasma in the blood vessels and fluids in the surrounding tissues. Albumin also serves as the carrier molecule for fatty acids and other small molecules in plasma.


A protein produced by immune system cells termed B-lymphocytes that is released into the tissues and bloodstream. Specific antibodies recognize and bind to specific molecules referred to as antigens and facilitate their elimination from the host.


A molecule or component thereof that when introduced into the body

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