Immune System Diseases - Biology As Poetry

AIDS

Virus-induced decline in T helper cells characterized by severe immunodeficiency.

AIDS stands for Acquired ImmunoDeficiency Syndrome and is caused by a viruses known as Human Immunodeficiency Virus (or HIV). These viruses infect a variety cell types within the body, including particularly T helper cells and macrophages.

The resulting declines in T helper cell populations results in the immunodeficiency of AIDS, though it can take years for AIDS to develop and this development occurs particularly as the resiliency of T helper cell populations, that is, ability to bounce back from virus-caused losses, is slowly depleted. At the same time, the immune system is needed to keep the HIV infection in check, and AIDS can be viewed in part as a positive feedback process whereby eventually the body's ability to hold back the replication of HIV is depleted by HIV-caused losses of T helper cells, which results in expansion of HIV populations at the further expense of T helper cells.

The resulting immunodeficiency makes the body particularly susceptible to a diversity of infectious diseases, which typically are the direct cause of death due to AIDS. Treatment for underlying HIV infections involves interfering in various ways with HIV replication using a diversity of antiviral drugs.

The above video does a good job of discussing what an HIV infection means including its symptomatic transition to AIDS; note that there is a possible "oops" at 2:00 where the narrator says, "…but as the body is forced to create new HIV cells…", presumably the word "viruses" would work better than "cells".

The above video does a good job of discussing what it means to progress from HIV infection to AIDS status.

Autoimmune disease

Lack of immune system tolerance for certain aspects of a body's own tissues, resulting in tissue destruction and/or chronic inflammation.

Autoimmune diseases result when self antigens instead are treated by the body as foreign antigens. This can occur when a pathogen produces antigens that are antigenically similar to self antigens. The pathogen may do this to increase its potential to evade the body's immune system by mimicking self antigens, which normally are ignored by the immune system ('normally', that is, given an absence of autoimmune disease).

If the pathogen stimulates an immune response in the course of infecting, and that immune response results in the generation of adaptive immune responses that also have an ability to recognize self antigens, then an autoimmune disease can commence. Examples of autoimmune diseases include type I diabetes (where the tissue attacked are the beta cells the islets of Langerhans), systemic lupus, and rheumatoid arthritis.

Allergy

Immune system hypersensitivity to a normally benign environmental component.

These environmental components are proteins that are associated with various types of organisms, including plants as well as animals. In individuals who are not allergic to the same substances, there is little or no harmful impact resulting from exposure. To individuals who are allergic, however, substantial consequences result including potentially life threatening constrictions of lung bronchioles.

These more severe allergic reactions are described as anaphylaxes (anaphylaxis is the singular) and often will increase in intensity given repeated allergen exposure. They may be treated over the short term with injections of the hormone epinephrine, which causes instead a dilation of bronchioles.

The above video provides a nice introduction to what allergies represent such as pollen allergies (this video is presented as well under the heading of allergen).

The above video does a reasonably good job of introducing the concept of food allergies, though note that the little pollen-looking things are meant represent food allergen molecules rather than pollen grains, which are much much larger than as depicted.

Anaphylaxis

Allergic reaction that is both substantial, including to the point of being lethal, and rapid in onset.

Anaphylaxes are pathological immune responses that are stimulated by repeated exposure to allergens and are described as hypersensitivities. Life-threatening anaphylaxis responses result for example in constriction of bronchioles and consequent restriction in breathing. As the hormone epinephrine stimulates the relaxation of bronchiole smooth muscle contraction, administration of epinephrine can result in a temporary reversal of these symptoms.

The above video walks you through what to do in response to a severe anaphylactic episode.

Immune Disorder