AIDS: Acquired Immune Deficiency Syndrome A disorder of immunity characterised by abnormalities of immunoregulation and opportunistic infections
Antibody A component of the immune system produced in response to exposure to antigens. Antibodies help eliminate infectious microorganisms in the body
Antigens A foreign molecule that stimulates the production of antibodies
AZT (zidovudine) A chemotherapy drug used to slow the progression of AIDS diseases by preventing viral replication. Its side-effects include leucopenia, anaemia, and nausea. Like all chemotherapy drugs, AZT is immunosuppressive
Cell-mediated immunity A defence mechanism involving the coordinated activity of two subpopulations of T lymphocytes, helper T4 cells and killer T8 cells. Helper T cells produce substances that stimulate and regulate other cells of the immune system
Cofactor A factor other than the basic causative agent of a disease that increases the likelihood of the disease developing
Cytomegalovirus (CMV) A virus belonging to the herpesvirus group, commonly associated with infections of patients who have received medical treatment involving immune suppression. In AIDS patients, CMV may produce pneumonia and inflammation in various organs
Cytopathic Disease-induced change to cells
ELISA Enzyme-linked immunosorbent assay, a test used to detect antibodies against HIV in blood samples
Encephalopathy Any degenerative disease of the brain. It is a major AIDS-defining illness although it is not necessarily caused by an infectious agent
Gay men A subgroup of homosexual men who identify themselves with the gay community sharing a common identity
Haemophilia A rare, hereditary bleeding disorder of males due to deficiency of Factor VIII blood-clotting proteins. Health. The state of physical and mental well-being, characterised by the absence of disease and infirmity
HIV — Human Immunodeficiency Virus A nine kilobyte retrovirus of the lentivirus family, believed to be cytopathic of T and B lymphocytes and haematopoietic stem cells, and associated with two types of cancer, encephalopathy, and 26 opportunistic infections
Human T-cell lymphotropic virus type III (HLTV-III) The name given in 1984 to isolates of the supposed AIDS-related retrovirus, called "HIV" since 1986. The isolate was not, as originally believed, of the HLTV family
HHV-6 A ubiquitous virus of the herpes family proposed as a cofactor with HIV in the aetiology of AIDS
Immune system A group of cells that confer protection against infectious agents. The cells are B and T lymphocytes and monocyte-macrophages. The products of these cells are antibodies and lymphokines. Much of the damage caused by a wide range of diseases is due to abnormal immune system responses
Immunosuppression The diminution of immune response
Kaposi's sarcoma An inflammation or a cancer of the lymphatic vessel walls, which usually appears as a violet or brownish skin blotch. It is a major AIDS-defining disease but it is not an infection
LAV Lymphadenopathy associated virus The name given in 1983 to the first isolate of the supposed AIDS-related virus, called "HIV" since 1986
Lentiviruses A subfamily of retroviruses that includes visna viruses of sheep and other animal viruses
Lifestyle The manners, habits, and consumption practices associated with specific social roles or with personal definitions of self
Lymphadenopathy Generalised swollen glands in the absence of an illness known to cause such symptoms
Lymphocytes A type of white cells found in most of the body's tissues. They stimulate production of antibodies against infection
Mycoplasma fermentans A derivative of the bacterium Mycobacterium avium-intracellulare, rarely found in humans prior to AIDS. It has been proposed as a cofactor in immune suppression
Nitrites ("poppers") A family of relaxant drugs heavily used by gay men after 1960. Nitrites are oxidising agents that cause cellular anoxia and impair cell-mediated immune response. They are also mitogenic, mutagenic and carcinogenic, and may interact with common substances, such as antihistamines, to produce toxic N-nitroso compounds
Opportunistic infection An infection caused by a microorganism that rarely induces disease in persons whose immune systems are normal
Oxidative stress A disturbance of the thiol cycle of cell metabolism leading to cell necrosis. Stress is caused by oxidising agents, such as recreational drugs, AZT, semen, antibiotics, and radiation therapy. Oxidative stress has been proposed as the mechanism of the immune system damage associated with AIDS
Provirus A copy of the genetic information of a retrovirus that is integrated into the DNA of an infected cell. Copies of the provirus are passed on to each of the infected cell's daughter cells
Retrovirus A family of viruses that contain the genetic material RNA and have the capacity to copy this RNA into the DNA of a cell. This process is called "reverse transcription"
Reverse transcriptase An enzyme produced by retroviruses that allows them to produce a DNA copy of their RNA
Safer sex Sexual behaviour that prevents the transmission of the HIV virus between partners. It is usually specified as preventing the exchange of blood, semen, and vaginal secretions. Seroconversion. The initial development of antibodies specific to an antigen. For HIV, seroconversion is believed to occur six to eight weeks after infection
Seropositive or HIV+ Having antibodies to HIV in the blood. In diseases other than AIDS, antibody response is usually interpreted to mean that the infectious agent has been immobilised
Syndrome A pattern of symptoms and signs, appearing one-by-one or simultaneously, that together characterise a particular disease
Syphilis A venereal disease caused by the spirochete Treponema pallidum and transmitted by sexual contact or in utero. Syphilis causes lesions to the skin and organs and may be latent for long periods
T lymphocytes (T cells) Cells of the immune system that originate in the thymus gland. They are found in the blood, lymph, and lymphoid organs
T4 cells Helper cells of the immune system that stimulate immune response. Also called CD4 lymphocytes. T8 (CD8) cells "turn off" T4 cell activity
Virus A non-living fragment of genes that lacks motility and metabolism and depends on the DNA of host cells for replication. Bacteria, plants, and animals are hosts to viruses. Virus are very small, having a mass of about one five hundred millionth of a T cell
Western Blot A test that identifies antibodies against specific protein molecules. Commonly used to confirm tests on samples found to be reactive to the ELISA test