The Immune System -- What Does It Mean?

AIDS

Acquired; not born with. Immune; your body's defense system. Deficiency; doesn't work properly. Syndrome; group of disorders and symptoms (not one, but several diseases).

Antibodies

Defense proteins produced by the immune system in response to "foreign" antigens. They counteract bacteria, viruses or other harmful germs. The antigen/antibody reaction forms one part of immunity.

Antigens

A substance which, upon entering the body, induces a state of sensitivity and immune response with the production of a specific antibody after a dormant period (days to weeks).

Beta-2 Macroglobulin

A protein found in blood. Higher than normal amounts of this protein means HIV is reproducing and the disease is progressing. (used as a marker before viral load availability)

Bone Marrow

Soft tissue located in the cavities of the bones where blood cells are formed.

Cd4 cells

Used loosely as an equivalent term for T-helper cells, these are the "big boss" of the immune system. They give direct orders for other cells to carry out.

Cd8 cells

Another kind of immune-system cell. These cells produce an unknown fluid which restricts HIV.

Chemistry Panels

A screening test of the most important chemicals in the blood. Such as electrolytes (salts); including sodium, potassium, proteins, and enzymes.

Complete Blood Count (CBC)

The name of a profile or group of tests, not a test itself. A screening of the most important cells in the blood. Includes the types and counting of white blood cells, the red blood count including hemoglobin, and platelet count.

Cytokine

A hormone-like substance that is produced and released by lymphocytes.

DNA

A complex protein that is the carrier of genetic information. HIV can insert itself into a cell's DNA and reproduce.

Hemoglobin

The component of red blood cells which carries oxygen.

IL-2

A protein called interleukin-2, produced by the immune system which stimulates the growth of T-cells. Also an immune-regulating drug.

Immune System

The complicated function of the body that recognizes foreign agents or germs, neutralizes them, and repeats the response later.

Immunity

A natural or acquired resistance to a specific disease; the general ability of a body to fight off disease.

Immunosuppression

Reduced function of one component of the body's immune system. HIV infection causes immunosuppression and other immune dysfunctions.

Interferon

A substance released by an infected cell which strengthens the defenses of nearby cells that are not yet infected. They are named according to their activity (interferon alpha, interferon gamma, etc.). Some have been made into immune regulating drugs.

Lymph nodes

Small bean-sized organs of the immune system, found throughout the body. Antigens which enter the body's blood are filtered out by lymph nodes, so that the rest of the immune system can attack the germ in the blood.

Lymphocyte

A type of white blood cell. T-helper cells are lymphocytes.

Macrophage

A large scavenger cell which devours decayed cells, blood tissue, and foreign particles. Macrophages exist in large numbers throughout the body, and are key to the development of immunity to a variety of organisms (living things). They are a storage place for HIV.

Microbes

Tiny living organisms such as bacteria, protozoa, and fungi; especially those which cause disease.

Monocyte

A large white blood cell which acts as a scavenger, capable of destroying bacteria, etc.. Also a storage place for HIV.

Mucous Membrane

A moist layer of tissue that lines body cavities which have an opening to the outside world, e.g., the lining of the mouth, nose, rectum or vagina.

Pathogenesis

The development of a disease; what happens to the body's cells, the body chemistry, and how the cells react.

Percentages

This is the number that tells you how much of your total lymphocytes (white blood cells) are actually T-cells. A normal CD4 percentage range is between 30 and 65%. CD4% is the percentage of CD4 to total lymphocytes; this is another important tool for monitoring your immune system. Your percentage gives you an overview of your T-cells in relation to the rest of your lymphocytes. Watch these trends along with CD4 counts.

Platelets

Cell parts which are critical for blood clotting and sealing off wounds.

Plasma

The 10% of the blood that contains nutrients, electrolytes (dissolved salts), gases, albumin, clotting factors, wastes and hormones.

Primary Infection

The initial introduction of an infection, such as HIV or herpes (for example), into a person. Primary HIV infection is displayed by a flu-like illness with fever, a general feeling of discomfort, and enlarged lymph glands.

Receptor

Protein on the cell endings or surface capable of receiving and transmitting activity. CD4's have receptors.

Red Blood Cells

Cells that carry oxygen throughout the body. Too many RBCs may slow down circulation. A low count may indicate anemia which can cause fatigue.

Retrovirus

A kind of virus, which takes genetic material from RNA then tricks the DNA into bringing "bad" information to cells. (HIV is a retrovirus).

RNA

A nucleic acid which takes genetic information from DNA and transfers it to the protein-making part of cells.

Stem Cell

A cell in the bone marrow which can grow into many different kinds of immune-system blood cells.

T-Helper Cells (T-Cells)

A critically important type of white blood cell (also known as CD4 or T4 cells) which help the body fight off infections. HIV invades these cells and weakens or destroys them. T-helper counts below 200 indicates severe immune suppression.

Triglyceride

A type of fatty cell that increases as a result of impaired fat metabolism caused by either HIV or medications.

T-Suppresser Cell

A type of white blood cell that helps regulate the body's response to an infection; also called CD8 or T8 cell.

Vaccine

A substance that contains antigenic components from an infectious organism. By stimulating an immune response (but not disease), it protects against subsequent infection by that organism. (see antigen)

Viral Load

A test to measure the amount of active HIV in the blood.

White Blood Cells

Cells which defend the body against infection. A high count may mean the body is fighting infection. A low count may mean a bone marrow problem. All white blood cells are called leukocytes.