Lesson 5 Immune System Diseases & Disorders

acute rejection

develops after several weeks of a transplant when unmatched antigens cause a reaction; usually antibody and T cells are involved which include a Type IV T cell mediated hypersensitivity reaction)

allografts

an organ transplant that happens between two members of the same species, but with a different genotype

antibodies (immunoglobulins—Ig)

Y- shaped proteins that are secreted by Plasma cells in order to recognize and eliminate antigens through neutralization, agglutination, precipitation, activation of complement, and opsonization.

antibody titer

Antibody concentration. A test is done to detect the presence and amount of antibodies in the blood. Can determine if a booster is needed, if there has been a recent infection, indicate an autoimmune disorder or if vaccinations have been effective.

antigen

toxin or other foreign substance which induces an immune response in the body (especially the production of antibodies)

autografts

a graft of tissue that is transferred from one position in the body to another position; of the same individual

autoimmune disorders

overactivity of the immune system causes the immune system to attack it's own tissues.

B lymphocytes

also known as B cells, proliferate to produce:
a) daughter Plasma cells which produce antibodies, and b) daughter B memory cells

Basophils

A type of granular leukocyte (WBC) that releases histamine and heparin that help in activating the immune response. Histamine stimulated inflammation. Heparin reduces clotting.

chronic/late rejection

Rejection of a transplant that occurs after months or years usually due to lesions causing arterial occlusion in transplanted organ that result in hypoxia within organ

complement system

complement proteins are produced by the liver and travel through the blood stream. They bind to foreign cells (e.g. bacteria) and :
a) provide opsonization which makes it easier for phagocytes to engulf and destroy bacteria
b) form MAC (membrance attack complex) which create portals in the bacteria making it leaky resulting in cell lysis and death
c) stimulate mast cells to release histamine and initiate inflmmation

ELISA

enzyme-linked immunosorbent assay (which is a test to detect antibody or antigen levels in the blood ; eg. detect the presence of anti-HIV antibodies which would indicate HIV infection)

Eosinophils

A granular type of WBC, which helps the immune system fight, and release toxins to help eliminate parasite infections.

gamma globulins

Also known as immunoglobulin (antibodies). Are present in plasma collected from donated human blood. These protective antibodies can be transfused into an individual who is ill with the same infection in order to help eliminate the pathogen.

hyperacute rejection

Immediately after transplantation (within minutes/hours); usually because the recipient has pre-existing antibodies against the graft's HLA antigens. This leads to degeneration of blood vessels resulting in lack of blood flow (ischemia to donated organ). Usually humoraly(antibody)mediated in a Type III hypersensitive immune reaction.

Immunity

the capability to resist harmful microorganisms

Immunosuppression

Reduced ability of the immune system to produce an immune response. Therefore the immune system is unable to defend the body from a pathogen properly.

Isografts

Tissue transferred between 2 genetically identical individuals. For example: Identical twins because they will have the exact same major histocompatibility complex proteins located on the surface of cells. These proteins are also known as HLA, Human Leukocyte Antigens or MHC, Major Histocompatibility Complexes.

Leukocytes

Classification of cells that circulate the blood stream to help fight infection and aid in immunity, also known as white blood cells (WBCs)

Lymphocytes

WBCs that are mainly found in the lymph and blood and take part in the immune response. There are 3 categories of lymphocytes:
a) NK, Natural Killer cells,
b) T lymphocytes, and
c) B lymphocytes

Macrophages

A large WBC that uses chemotaxis to find bacteria and then phagocytose or engulf and destroy bacteria, virus-infected cells, and parasites.

major histocompatibility complex

The MHC is a set of cell surface proteins essential for acquired immune system to recognize foreign cells.

Memory cells

long lived T and B lymphocytes that respond quickly when exposed to a specific antigen

Monocytes

a type of leukocyte that differentiates into macrophages

Neutrophils

most common type of white blood cells that are the first to reach the site of infection and phagocytose foreign objects.

opportunistic microorganisms

an organism that would normally not cause an infection in a healthy individual, but once that individual is immunocompromised or there is a portal of entry, the organism is now able to cause an infection

primary deficiency

a nutritional deficiency due to a decreased intake of food. When energy input is less than the energy output, or than what is required by the individual to maintain their health.

Prophylactic

a medication or treatment used for the prevention of disease or illness

secondary deficiencies

acquired when the immune system is compromised due to an environmental factor (ex: malnutrition, chemo)

T lymphocytes

these leukocytes are a part of the immune system and develop from hematopoietic stem cells in the bone marrow and mature in the thymus. Their purpose is to protect the body and they secrete chemicals to attack infected or cancerous cells. They also stimulate the growth of more T cells to continue the process.

Type I (allergic) reactions

anaphylactic reactions (immediate hypersensitivity), these reactions are either localized or systemic. Reactions may include hives, redness, etc. This occurs due to linking with IgE antibody of mast cells. The IgE recognizes an antigen that is not harmful to the body.

Type II reactions

hypersensitivity, antibody-dependent process where antibodies bind to antigens causing damage to tissue.

Type III reactions

build up of antibody complexes that havent been cleared by immune cells causing an inflamation.

Type IV reactions

Reaction resulting from antigens binding to T lymphocytes which are then stimulated to release lymphokines. Type of reaction produces contact dermatitis and transplant rejections.

Xenografts

a type of transplant where the donor is a different species than the person receiving the transplant.