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AIDSinfo Glossary Search

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B Cell

Also known as: B Lymphocyte

B Lymphocyte Audio (En español)

Also known as: B Cell

A type of lymphocyte. B lymphocytes (B cells) produce antibodies to help the body fight infection.

See Related Term(s): Antibody, Lymphocyte

B-Cell Lymphoma Audio (En español)

A type of lymphoma (cancer of the lymphatic system) that starts in the B lymphocytes (B cells). People with weakened immune systems, including people with HIV, are at a higher risk for B-cell lymphomas than people with healthy immune systems. In people infected with HIV, certain B-cell lymphomas are considered AIDS-defining conditions.

See Related Term(s): AIDS-Defining Condition, B Lymphocyte, Lymphoma


Also known as: BID


Also known as: Beta-2 Microglobulin

Bactericide Audio (En español)

A drug used to kill bacteria.

See Related Term(s): Bacterium

Bacteriostat Audio (En español)

A drug used to prevent the growth of bacteria. Bacteriostats do not kill bacteria.

See Related Term(s): Bactericide, Bacterium

Bacterium Audio (En español)

A single-celled microorganism. Bacteria occur naturally almost everywhere on earth, including in humans. Some bacteria can cause disease in humans. People with weakened immune systems, including people with HIV, are at a higher risk for bacterial infections than people with healthy immune systems.

Bartonellosis Audio (En español)

A group of infections caused by the bacteria Bartonella. Examples of the various infections include cat scratch disease, trench fever, bacillary angiomatosis (BA), and bacillary peliosis hepatis. BA and bacillary peliosis hepatis occur only in people with weakened immune systems, such as people with HIV.

See Related Term(s): Opportunistic Infection

Baseline Audio (En español)

An initial measurement used as the basis for future comparison. For people infected with HIV, baseline testing includes CD4 count, viral load (HIV RNA), and resistance testing. Baseline test results are used to guide HIV treatment choices and monitor effectiveness of antiretroviral therapy (ART).

Basic Chemistry Profile

Also known as: Comprehensive Metabolic Panel

Basophil Audio (En español)

A type of white blood cell that helps the body fight infection by triggering an inflammatory response to an antigen.

See Related Term(s): Antigen, White Blood Cell


Also known as: Quantitative Branched DNA

Beta-2 Microglobulin (B2M) Audio (En español)

A protein found on the surface of many cells, including white blood cells. Beta-2 microglobulin (B2M) levels increase during infection with some viruses, including HIV.

BID Audio (En español)

Also known as: bid, b.i.d.

An abbreviation meaning "two times a day." The abbreviation is commonly used in drug dosing instructions.


Also known as: BID

Bilirubin Audio (En español)

A reddish-yellow substance produced during the normal breakdown of red blood cells. Bilirubin is normally processed through the liver and eventually excreted from the body. Excess bilirubin in the blood may indicate liver damage or disease.

See Related Term(s): Jaundice, Liver, Liver Function Test

Bioavailability Audio (En español)

A measure of the rate and extent to which a drug is absorbed and becomes available at the site of drug action in the body.

See Related Term(s): Pharmacology

Biopsy Audio (En español)

Removal of tissue, cells, or fluid from the body for examination under a microscope. Biopsies are used to diagnose disease.

Black Box Warning

Also known as: Boxed Warning

Black Label Warning

Also known as: Boxed Warning

Blip Audio (En español)

A temporary, detectable increase in the amount of HIV in the blood (viral load) that occurs after antiretroviral therapy (ART) has effectively suppressed the virus to an undetectable level. Isolated blips are not considered a sign of virologic failure.

See Related Term(s): Undetectable Viral Load, Viral Load, Virologic Failure

Blood Sugar

Also known as: Glucose

Blood Thinner

Also known as: Anticoagulant

Blood-Brain Barrier Audio (En español)

A semi-permeable layer of tightly joined cells that separate the brain from circulating blood. The blood-brain barrier prevents potentially dangerous substances in the blood, such as disease-causing organisms or chemical compounds, from entering the brain tissue. Certain antiretroviral (ARV) drugs can cross the blood-brain barrier and may help stop or slow HIV damage to the brain.

Body Habitus Changes Audio (En español)

Noticeable physical changes in body shape or appearance. In people with HIV, these changes may be due to HIV infection, opportunistic infections, or antiretroviral (ARV) drugs.

See Related Term(s): Gynecomastia, Lipodystrophy, Wasting Syndrome

Bone Density Test

Also known as: Dual Energy X-Ray Absorptiometry

Bone Marrow Audio (En español)

The soft, sponge-like tissue in the center of bones. There are two types of bone marrow: yellow (made up of mostly fat cells) and red (the source of red blood cells, platelets, and most white blood cells).

Bone Marrow Suppression

Also known as: Myelosuppression

Boosting Audio (En español)

Using an antiretroviral (ARV) drug to increase the effectiveness of another ARV drug. For example, drugs in the protease inhibitor (PI) ARV drug class are often boosted with the ARV drug ritonavir.

See Related Term(s): Protease Inhibitor

Boxed Warning Audio (En español)

Also known as: Black Box Warning, Black Label Warning

The strongest form of warning required by the Food and Drug Administration (FDA) for prescription drug labeling. A boxed warning alerts health care providers and consumers to increased risk of serious adverse reactions associated with use of a drug or to restrictions on use of a drug. The boxed warning is presented in a box surrounded by a black border and is placed on the drug label and any package inserts or promotional materials intended for the prescriber or patient.

See Related Term(s): Food and Drug Administration, Package Insert

Brain Attack

Also known as: Stroke


Also known as: Pneumonia

Bronchoscopy Audio (En español)

A procedure used to look inside the airways of the lungs. The procedure is done using a bronchoscope, a flexible tube that has a camera on one end of it. A bronchoscopy may be used to diagnose HIV-related infections or cancer.

Bronchospasm Audio (En español)

Sudden, involuntary contraction of the muscles of the bronchii (airways in the lungs).

Budding Audio (En español)

The sixth of seven steps in the HIV life cycle. During budding, new HIV RNA and HIV proteins made by the host cell move to the surface of the host cell and assemble into an immature (noninfectious) HIV. After the immature HIV is formed, the virus pushes itself out of the host cell, taking with it part of the host cell’s outer membrane.

See Related Term(s): Life Cycle

Buffalo Hump

Also known as: Dorsocervical Fat Pad

Burkitt Lymphoma Audio (En español)

Also known as: Burkitt's Lymphoma

A fast-growing type of B-cell non-Hodgkin lymphoma (cancer of the lymphatic system). In people with HIV, Burkitt lymphoma is considered an AIDS-defining cancer.

See Related Term(s): Lymphoma, Non-Hodgkin Lymphoma

Burkitt's Lymphoma

Also known as: Burkitt Lymphoma

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