I D
Identification.

IDU
See "Injection drug user"

IDIOTYPES
The unique and characteristic parts of an antibody's variable region, which can themselves serve as antigens.

IL 1-12
See "Interleukins 1-12"

IM
See "Intramuscular"

IMMUNE COMPLEX
Clusters formed when antigens and antibodies bind together.

IMMUNE DEFICIENCY
A breakdown or inability of certain parts of the immune system to function, thus making a person more susceptible to certain diseases to which the person would not ordinarily be subject. In disease associated with HIV, cell mediated immunity related to the function of T-helper lymphocytes deteriorates, increasing the likelihood of disease from a number of pathogens, many of which are ubiquitous (opportunistic infection).

IMMUNE RESPONSE
The activity of the immune system against foreign substances.

IMMUNE SYSTEM
The complex functions of the body that recognize foreign agents or substances, neutralize them, and recall the response later when confronted with the same challenge.

IMMUNE THROMBOCYTOPENIC PURPURA (ITP)
An HIV-related loss of platelets in the blood. Its exact cause is unclear.

IMMUNITY
A natural or acquired resistance to a specific disease. Immunity may be partial or complete, long lasting or temporary.

IMMUNOCOMPETENT
Having a normally functioning immune system.

IMMUNOCOMPROMISED
Having a deficient or damaged immune response.

IMMUNOGLOBULIN
A protein that acts as an antibody to help the body fight off disease. There are 5 classes: IgG, IgA, IgD, IgM and IgE. Recombinant and pooled immunoglobulins from blood donations have been used successfully to help HIV-infected children and some adults resist bacterial infections.

IMMUNOMODULATOR
Any substance that influences the immune system. Generally the term "immunomodulator" is used.

IMMUNOSUPPRESSION
A state of the body in which the immune system is damaged and does not perform its normal functions. Immunosuppression may be induced by drugs or result from certain disease processes (such as HIV infection).

IMMUNOTHERAPEUTIC
Aiming at reconstituting an impaired immune system.

INDINAVIR
An experimental protease inhibitor drug made by Merck pharmaceuticals

IN UTERO
Latin for "in the uterus," or womb.

INVIRASE
A Brand name for Saquinavir

IN VIVO
Latin for "in life" : Studies conducted within a living organism, e.g., animal or human studies.

IN VITRO
Latin for "in glass": An artificial environment created outside a living organism, e.g., a test tube or culture plate, used in experimental research to study a disease or process.

INACTIVE CONTROL TREATMENT
A control treatment that is not considered to have any pharmacological or physiological effect. A placebo treatment or sham procedure. See also "Active Control Treatment."

INCUBATION PERIOD
The time interval between the initial infection and appearance of the first clinical symptom or sign of disease.

IND
See "Investigational drug status".

INDICATION
Sign or symptom. Also, in terms of drug approval, the exact cause or purpose for which a drug is approved by the FDA to be prescribed. Also called "label indication"

INDOLENT
At rest, or in a quiescent state.

INDUCED SPUTUM
A test where saline mist is breathed to induce a cough. Resultant sputum is then cultured or stained to look for microorganisms, often pneumocystis carinii.

INDUCTION
The initiation of a particular therapy.

INFECTION
Condition in which virulent organisms are able to multiply within the body and cause a response from the host's immune defenses. Infection may or may not lead to clinical disease.

INFECTIOUS
Capable of being transmitted by infection, with or without actual contact.

INFILTRATES
Something seeping or filling in a space or cavity.

INFLAMMATION
Redness, swelling, soreness of tissues.

INFORMED CONSENT
The voluntary consent given by a patient to participate in a study after being informed of its purpose, method of treatment, procedure for assignment to treatment, benefits and risks associated with participation, and required data collection procedures and schedule.

INFUSION
Administration of treatment in a dilute form by slow injection into a vein.

INH
See "Isoniazid"

INJECTION DRUG USER (IDU, IVDU, AVDA)
Also known as intravenous drug user (IVDU), or intravenous drug abuser (IVDA). None of these terms are very precise: often IVDU will be used to describe someone who injects IM or Sub-Q, and the distinction between "user" and "abuser" is a controversial and emotionally charged one. Nevertheless, a working definition for an IDU is anyone who regularly injects any substances, whether pharmaceutically or illicitly made, not under medical prescription and supervision.

INSTITUTIONAL REVIEW BOARD (IRB)
A committee of physicians, statisticians, community advocates, and others which ensures that a clinical trial is ethical and that the rights of the study participants are protected. All clinical trials in the United States must be approved by an IRB before they begin.

INTENTION-TO-TREAT ANALYSIS
A method of data analysis in which the primary tabulations, summaries and comparisons of patient outcome data are by assigned treatment, regardless of compliance to therapy or the protocol.

INTEGRASE
The HIV enzyme that governs the insertion of HIV's proviral genetic material into the host genome. Integrase is a target for a new generation of HIV drugs.

INTERACTION
A situation in which the magnitude of the test-control treatment difference for the outcome of interest depends upon the value assumed by a third factor, such as age or prior disease state of the study patients.

INTERACTION EFFECT
Treatment interaction effect.

INTERCURRENT
Occurring at the same time, or accompanying.

INTERFERONS
A family of secreted proteins (lymphokines) in the body with the ability to induce an antiviral state in most cell types. They are secreted by infected host cells to protect uninfected cells from viral infections. There are 3 main classes of interferon: alpha, beta and gamma. The interferons have been synthesized by genetic engineering, and are being tested as treatments for HIV infections and other diseases. Alpha interferon is FDA-approved for treatment of HIV-related Kaposi's sarcoma, chronic hepatitis B and genital warts.

INTERIM ANALYSIS
Any data analysis done before the trial is finished, for whatever reason, but usually concerned with assessments of treatment effects.

INTERIM RESULT
1. Any test-control treatment difference observed during the trial. 2. A test-control treatment difference observed during the trial that results in a treatment protocol change.

INTERLEUKIN
A chemical hormone messenger (cytokine) secreted by and affecting many different cells in the immune system.

INTERLEUKIN-1 (IL-1)
A natural cytokine released by monocytes, macrophages, T-cells and other immune cells that fights infection.

INTERLEUKIN-2 (IL-2)
A cytokine that is produced by both T-helper and suppresser lymphocytes, IL-2 increases the expression of natural killer and other cytotoxic cells. IL-2 is associated with a cell-mediated or TH-2 immune response. A recombinant IL-2 is under study as a treatment for HIV disease (immunomodulator).

INTERLEUKIN-4 (IL-4)
A cytokine released by lymphocytes (the TH-2 subset of T-helper lymphocytes) that enhances the humoral response, increasing antibody production.

INTERLEUKIN 6 (IL-6)
A cytokine whose production affects many different cells in the immune system.

INTERLEUKIN-10 (IL-10)
A cytokine released by lymphocytes (the TH-2 subset of T-helper lymphocytes) that enhances the humoral response, increasing antibody production.

INTERLEUKIN-12 (IL-12)
A cytokine that induces the production of natural killer and other cytotoxic immune cells. IL-12 is associated with a cell-mediated or TH-1 immune response. A recombinant IL-12 is under study as a treatment for HIV disease (immunomodulator).

INSTERSTITIAL
A space or gap in a tissue: in the context of "interstitial infiltrates", means between the air passage in a lung

INTOLERANT
Unable to take a drug because of toxicity.

INTRADERMAL
Within the layers of the skin.

INTRALESIONAL
Injected directly into a lesion

INTRAMURAL
Research that is done at the National Institutes of Health, by one or more institute, often within the NIH clinical research facility.

INTRAMUSCULAR
Into the muscle: frequently in reference to injections.

INTRAPARTUM
During childbirth.

INTRATHECAL
Injection of a substance through the theca of the spinal cord into the subarachnoid space.

INTRAVENOUS (IV)
Within or into the veins. Intravenous drugs are injected directly into the veins.

INTRAVlTREAL
Injected in to the vitreous humor of the eye.

INVESTIGATIONAL
Under study

INVESTIGATIONAL NEW DRUG APPLICATION
(INDA, also IND) An application directed to the Food and Drug Administration (made by submitting a Notice of Claimed Investigational Exemption for a New Drug) for permission to evaluate a drug (new or old) for a new indication in humans.

IRB
See "Institutional review board".

ISONIAZID
An antibiotic that is one of the most common components in treatment for tuberculosis, either alone or in combination.

ISOSPORIASIS
A Protozoal infection, isosporiasis is usually restricted to the lower gastrointestinal tract. Symptomatically similar to cryptosporidiosis, isosporiasis usually responds well to treatment.

ISOTONIC
Refers to a solution whose salinity is the same as human blood.

ITRACONAZOLE (SPORANOX)
An antifungal drug that is used to treat fungal infections in persons with HIV, including candida, cryptococcus, histoplasmosis, and others.

IV
See "Intravenous"

IVDA
See IDU

IVDU
See IDU