Idiopathic
Thrombocytopenia Purpura (ITP)
A rare autoimmune disorder characterized by a shortage
of platelets in the blood, which results in bruising
and spontaneous bleeding.
Immune
Reconstitution Syndrome (IRS)
Also known as immune restoration disease (IRD) or immune
reconstitution inflammatory syndrome (IRIS). An inflammatory
reaction that can occur when an immunocompromised person's
immune system improves, such as when a person with HIV
disease begins anti-HIV treatment and experiences a
rise in CD4 cell count. Fever, along with swelling,
redness, or discharge at the site of an injury or infection,
may signal that an infection previously unnoticed by
a weak immune system is now a target of a stronger immune
system. Although IRS indicates that a person's immune
system has grown healthier, it can be a serious, sometimes
fatal condition and must be treated aggressively.
Immune Response
The body's defensive reaction to a foreign invader,
such as a virus, bacteria, or fungus. The immune response
includes both humoral (antibody-based) and cell-mediated
immunity.
Immune System
The collection of cells and organs whose role is to
protect the body from foreign invaders. Includes the
thymus, spleen, lymph nodes, B and T cells, and antigen-presenting
cells.
Immunity
Protection against or resistance to disease.
Immunologic Failure
An HIV-infected individual is said to be experiencing
immunologic failure if the individual's CD4 count decreases
below his or her baseline count or does not increase
above the baseline count within the first year of anti-HIV
treatment. People with virologic failure who do not
switch to an effective drug regimen usually progress
to immunologic failure within about 3 years. Immunologic
failure may be followed by clinical failure.
Immunomodulator
A natural or man-made substance that can modify the
functioning of the immune system.
Immunosuppression
Inability of the immune system to function normally.
May be caused by drugs (for example, chemotherapy),
or result from certain diseases (for example, HIV infection).
Immunotherapy
Treatment to stimulate or restore the body's immune
system to fight disease.
In Vitro
Latin for "in glass." A term meaning that
a research study was conducted in an artificial environment
created outside a living organism (for example, in a
test tube or petri dish).
In Vivo
Latin for "in life." A term meaning that a
research study was conducted in a living organism (animal
or human).
Incidence
The rate of occurrence of new cases of a particular
disease in a given population. Often reported as number
of cases per 100,000 people.
Inclusion/Exclusion Criteria
A specific set of selection rules that determine whether
a person is eligible to enroll in a particular clinical
trial. For example, some trials may not accept people
with chronic liver disease or with certain drug allergies.
Others may exclude men or women, or only include people
with a certain CD4 count or viral load.
Indian Health
Service (IHS)
The agency within the U.S. Department of Health and
Human Services (DHHS) responsible for providing Federal
health services to American Indians and Alaska Natives.
Infection
Establishment of an infectious micro-organism in a suitable
host. The term is also used to refer to disease caused
by an infectious micro-organism.
Infectious
Capable of causing infection.
Informed Consent
A person's agreement to participate in a clinical trial
after understanding all aspects of the trial, including
potential risks and benefits.
Institutional
Review Board (IRB)
A committee of experts who review and monitor clinical
trials to ensure that they are ethical and that the
rights of study participants are protected. Federal
regulations dictate that any institution that conducts
or supports clinical trials must have an IRB.
Insulin Resistance
An abnormal body response to insulin, a hormone that
regulates glucose (sugar) levels. People with insulin
resistance have abnormally high blood levels of insulin,
which may lead to heart and cholesterol problems and
obesity. Insulin resistance may occur in HIV-infected
individuals taking certain PIs.
Integrase
An HIV protein that plays an important role in the virus's
life cycle. Integrase inserts HIV's genetic information
into the infected cell's own DNA.
Integrase Inhibitors
A class of anti-HIV drugs that prevents the HIV integrase
protein from inserting HIV's genetic information into
an infected cell's own DNA.
Integration
The process by which HIV integrase inserts HIV's genetic
material into an infected cell's own DNA. This crucial
step in HIV's life cycle is targeted by the class of
anti-HIV drugs called integrase inhibitors.
Intensification
Adding additional anti-HIV drugs to an existing treatment
regimen, usually because that regimen failed to adequately
control HIV replication.
Interferon (IFN)
A cytokine (protein that regulates immune system activity)
that the body produces to fight viruses. Laboratory-made
versions of IFN are used in the treatment of some virus
infections and cancers. There are three main types of
interferon: alpha, beta, and gamma. IFN alpha is used
to treat hepatitis C virus (HCV) infection and many
cancers, including Kaposi's sarcoma.
Interleukin-2 (IL-2)
A cytokine (protein that regulates immune system activity)
that can increase the production of certain disease-fighting
white blood cells. During HIV infection, IL-2 levels
gradually decline. A laboratory-made version of IL-2
is used to treat some cancers and has been studied as
a way to increase the number of CD4 cells and other
immune system cells in people with HIV.
Interleukin-7 (IL-7)
A substance produced in small amounts in bone marrow
cells that increases the body's production of certain
disease-fighting white blood cells. Laboratory-produced
IL-7 is a drug product that appears to induce HIV replication
in latent, or resting, infected cells. Activation of
HIV in resting cells allows antiretroviral drugs to
target HIV in those cells.
Interstitial Nephritis
A kidney disorder caused by inflammation of the small
spaces between parts of the kidney. The condition is
a potential side effect of certain anti-HIV drugs.
Intramuscular (IM)
Relating to the area within a muscle. Intramuscular
also refers to an injection made directly into a muscle.
Intrapartum
The time period spanning labor and delivery.
Intravaginal
Within the vagina.
Intravenous
Inside a vein. Intravenous also refers to an injection
made directly into a vein.
Intravenous
Immunoglobulin (IVIG)
A solution of antibodies taken from healthy donors and
injected into the veins of people with low or abnormal
antibody production to help protect them from infections.
Investigational Drug
Also known as experimental drug. A drug that has not
been approved by the FDA to treat a particular disease
or condition. The safety and effectiveness of an investigational
drug must be tested in clinical trials before the manufacturer
can request FDA approval for a specific use of the drug.
Investigational
New Drug Application (IND)
The process through which data about an experimental
drug is submitted to and reviewed by the Food and Drug
Administration (FDA) before the drug is allowed to be
tested in clinical trials.
Isosporiasis
An infection caused by the protozoan Isospora belli,
which enters the body through contaminated food or water.
Symptoms include diarrhea, fever, headache, abdominal
pain, vomiting, and weight loss. Isosporiasis is considered
an AIDS-defining condition in people with HIV.
