3TC
Lamivudine T4 Cell
(Also called T-helper cell.) Antibody-triggered immune cells that seek and attack invading microorganisms. Macrophages summon T4 cells to the infection site. There, the T4 cell reproduces and secretes potent chemicals that stimulate B cells to produce antibodies, signal natural killer or cytotoxic (cell-killing) T cells, and summon other macrophages to the infection site. In healthy immune systems, T4 cells are twice as common as T8 cells. TB, TBC
See
Tuberculosis (TB). T Cells
(T lymphocytes) T cells are white blood cells derived from the thymus gland that participate in a variety of cell-mediated immune reactions. Three fundamentally different types of T cells are recognized helper, killer, and suppressor. They are essential for a normal functioning immune system. TDF
Tenofovir disoproxil fumarate Teratogenicity
The production of physical defects in offspring in utero (i.e. causing birth defects). Teratogenicity is a potential side effect of some drugs, such as thalidomide. Tetanus
An acute, often fatal infectious disease caused by the bacterium Clostridium tetani. The agent usually enters the body through contaminated puncture wounds (eg, those caused by metal nails, wood splinters, or insect bites), although other portals of entry include burns, surgical wounds, the umbilical stump of neonates, and the postpartum uterus. The disease can be prevented by immunizing with tetanus toxoid. Therapeutic HIV Vaccine
Also called treatment vaccine. A vaccine designed to boost the immune response to HIV infection. A therapeutic vaccine is different from a preventive vaccine, which is designed to prevent an infection or disease from becoming established in a person. Therapy
Any form of treatment. Drugs, radiation, and psychiatric counseling are forms of therapy. Thrombocytopenia
A decreased number of blood platelets (cells important for blood clotting). See
Platelets; Immune Thrombocytopenic Purpura (ITP). Thrush
Sore patches in the mouth caused by the fungus Candida albicans. Thrush is one of the most frequent early symptoms or signs of an immune disorder. The fungus commonly lives in the mouth, but only causes problems when the body's resistance is reduced either by antibiotics that have reduced the number of competitive organisms in the mouth or by an immune deficiency such as HIV disease. See
Candidiasis . Thymus
A mass of glandular tissue (lymphoid organ) found in the upper chest under the breastbone in humans. The thymus is essential to the development of the body's system of immunity beginning in fetal life (i.e. before birth). The thymus processes white blood cells (lymphocytes), which kill foreign cells and stimulate other immune cells to produce antibodies. TID
Three times each day Tissue
A collection of similar cells acting together to perform a particular function. There are four basic tissues in the body: epithelial, connective, muscle, and nerve. Titer (Titre)
A laboratory measurement of the amount--or concentration--of a given compound in solution. TIW
Three times each week T Lymphocytes
See
T Cells. TMP/SMZ
Trimethoprim/sulfamethoxazole (generic name); Cotrimoxazole, Bactrim, Septra (trade names). TOT
Training of trainers Total Lymphocyte Count
A count of the number of lymphocytes (white blood cells) in the blood. Toxicity
The extent, quality, or degree of being poisonous or harmful to the body. Toxoplasmic Encephalitis
See
Toxoplasmosis. Toxoplasmosis (toxo)
An opportunistic infection caused by the protozoan parasite Toxoplasma gondii, which is found in undercooked meat and cat feces. A common manifestation is toxoplasmic encephalitis, characterized by brain swelling, confusion, lethargy, and possible coma. Transaminase
A liver enzyme. A laboratory test that measures transaminase levels is used to assess the functioning of the liver. Transfusion
The process of transfusing fluid (such as blood) into a vein. Transmission
In the context of HIV disease, HIV is spread most commonly by sexual contact with an infected partner. The virus can enter the body through the mucosal lining of the vagina, vulva, penis, rectum, or, rarely, the mouth during sex. The likelihood of transmission is increased by factors that may damage these linings, especially other sexually transmitted diseases that cause ulcers or inflammation. HIV also is spread through contact with infected blood, most often by the sharing of drug needles or syringes contaminated with minute quantities of blood containing the virus. Children can contract HIV from their infected mothers either during pregnancy or birth, or postnatally through breast-feeding. In developed countries, HIV is now rarely transmitted by transfusion of blood or blood products because of screening measures. Transplacental
Across or through the placenta. Usually refers to the exchange of nutrients, waste products, and other materials (e.g. drugs) between the developing fetus and the mother. Also refers to transmission of virus such as HIV across the placenta to the infant. Treatment Failure
Inability of a medical therapy to achieve the desired results. Triglyceride
A compound made up of a fatty acid (such as oleic, palmitic, or stearic acid) and glycerol. Triglycerides make up most animal and vegetable fats and are the basic water-insoluble substances (lipids) that appear in the blood where they circulate. Trimethoprim/Sulphamethoxazole
(Cotrimoxazole, Bactrim) A combination antibiotic drug effective at preventing and treating Pneumocystis jiroveci pneumonia (PCP); also serves as a prophylaxis against toxoplasmosis. T Suppressor Cells
T lymphocytes responsible for turning off the immune response after an infection is cleared. They are a subset of the CD8+ lymphocytes. Tuberculin Skin Test (TST)
A purified protein derivative (PPD) of the tubercle bacilli, called tuberculin, is introduced into the skin by scratch, puncture, or intradermal injection. If a raised, red, or hard zone forms around the test site, the person is said to be sensitive to tuberculin, and the test is read as positive. Tuberculosis (TB)
Infection with the bacteria Mycobacterium tuberculosis, as evidenced by a positive tuberculin skin test (TST) that screens for infection with this organism. Sometimes, TST is called a purified protein derivative (PPD) or Mantoux test. A positive skin test might or might not indicate active TB disease. Thus, any person with a positive TST should be screened for active TB and, once active TB is excluded, evaluated for treatment to prevent the development of TB disease. TB infection alone is not considered an opportunistic infection indicating possible immune deficiency. | 
