"Slow" virus characterized by a long interval between infection and the onset of symptoms. HIV is a lentivirus, as is the simian immunodeficiency virus (SIV) that infects non-human primates.

A general term to describe an area of altered tissue (e.g., the infected patch or sore in a skin disease).

Any of the various white blood cells that together make up the immune system. Neutrophils, lymphocytes, and monocytes are all leukocytes.

An abnormally high number of leukocytes in the blood. This condition can occur during many types of infection and inflammation.

A decrease in the number of white blood cells. The threshold value for leukopenia is usually taken as less than 5,000 white blood cells per cubic millimeter of blood.

A whitish lesion that appears on the side of the tongue and inside cheeks. The lesion appears raised, with a ribbed or hairy surface. OHL occurs mainly in persons with declining immunity and may be caused by Epstein-Barr virus infection. OHL was not observed before the HIV epidemic.

Any of a group of fats and fatlike compounds, including sterols, fatty acids, and many other substances.

A disturbance in the way the body produces, uses, and distributes fat. Lipodystrophy is also referred to as buffalo hump, protease paunch, or Ceridian potbelly. In HIV disease, lipodystrophy has come to refer to a group of symptoms that seem to be related to the use of protease inhibitor and NRTI drugs. How protease inhibitors and NRTI’s may cause or trigger lipodystrophy is not yet known. Lipodystrophy symptoms involve the loss of the thin layer of fat under the skin, making veins seem to protrude; wasting of the face and limbs; and the accumulation of fat on the abdomen (both under the skin and within the abdominal cavity) or between the shoulder blades. Women may also experience narrowing of the hips and enlargement of the breasts. Hyperlipidemia and insulin resistance are frequently associated with lipodystrophy.

A spherical particle in an aqueous (watery) medium (e.g., inside a cell) formed by a lipid bilayer enclosing an aqueous compartment. Microscopic globules of lipids are manufactured to enclose medications. The fatty layer of the liposome is supposed to protect and confine the enclosed drug until the liposome binds with the outer membrane of target cells. By delivering treatments directly to the cells needing them, drug efficacy may be increased while overall toxicity is reduced.

A test that measures the blood serum level of any of several enzymes (e.g., SGOT and SGPT) produced by the liver. An elevated liver function test is a sign of possible liver damage.

The genetic material at each end of the HIV genome. When the HIV genome is integrated into a cell's own genome, the LTR interacts with cellular and viral factors to trigger the transcription of the HIV-integrated HIV DNA genes into an RNA form that is packaged in new virus particles. Activation of LTR is a major step in triggering HIV replication.

Individuals who have been living with HIV for at least 7 to 12 years (different authors use different time spans) and have stable CD4+ T cell counts of 600 or more cells per cubic millimeter of blood, no HIV-related diseases, and no previous antiretroviral therapy. Data suggest that this phenomenon is associated with the maintenance of the integrity of the lymphoid tissues and with less virus trapping in the lymph nodes than is seen in other individuals living with HIV.

A transparent, slightly yellow fluid that carries lymphocytes. Lymph is derived from tissue fluids collected from all parts of the body and is returned to the blood via lymphatic vessels.

Small, bean-sized organs of the immune system, distributed widely throughout the body. Lymph fluid is filtered through the lymph nodes in which all types of lymphocytes take up temporary residence. Antigens that enter the body find their way into lymph or blood and are filtered out by the lymph nodes or spleen, respectively, for attack by the immune system.

Swollen, firm, and possibly tender lymph nodes. The cause may range from an infection such as HIV, the flu, or mononucleosis to lymphoma (cancer of the lymph nodes).

A body-wide network of channels, similar to the blood vessels that transport lymph to the immune organs and into the bloodstream.

A white blood cell. Present in the blood, lymph, and lymphoid tissue.

A type of pneumonia that affects 35 to 40% of children with AIDS, and which causes hardening of the lung membranes involved in absorbing oxygen. LIP is an AIDS-defining illness in children. The cause of LIP is not clear. There is no established therapy for LIP, but the use of corticosteroids for progressive LIP has been advocated.

Include tonsils, adenoids, lymph nodes, spleen, thymus, and other tissues. These organs act as the body's filtering system, trapping invaders (foreign particles, e.g., bacteria and viruses) and presenting them to squadrons of immune cells that congregate there. Within these lymphoid tissues, immune activity is concentrated in regions called germinal centres, where the thread-like tentacles of follicular dendritic cells (FDCs) form networks that trap invaders.

Lymphocytes transformed in the laboratory into lymphokine activated killer cells, which attack tumour cells.

Cancer of the lymphoid tissues. Lymphomas are often described as being large cell or small cell types, cleaved or non-cleaved, or diffuse or nodular. The different types often have different prognoses (i.e., prospect of survival or recovery). Lymphomas can also be referred to by the organs where they are active, such as CNS lymphomas, which are in the central nervous system, and GI lymphomas, which are in the gastrointestinal tract. The types of lymphomas most commonly associated with HIV infection are called non-Hodgkin's lymphomas or B cell lymphomas. In these types of cancers, certain cells of the lymphatic system grow abnormally. They divide rapidly, growing into tumours.

A relative or absolute reduction in the number of lymphocytes in the circulating blood

A specific immune response that entails rapid T cell replication. Standard antigens, such as tetanus toxoid, that elicit this response, are used in lab tests of immunocompetency.

Rupture and destruction of a cell.