Ch 18 Immune Disorders Flashcards
Hypersensitivity
also known as allergy, this is when the immune system reacts in an exaggerated or inappropriate way to a foreign substance
4 types of Hypersensitivity
(Type I) Immediate
(Type II) Cytotoxic
(Type III) Immune Complex
(Type IV) Delayed (cell mediated)
Immediate Hypersensitivity (Type I)
also known as anaphylaxis; results from a prior exposure to a foreign substance called an allergen, which is an antigen that provokes a hypersensitivity response. Involves antibodies
Cytotoxic Hypersensitivity (Type II)
elicited by antigens in cells, especially red blood cells, that the immune system recognizes as foreign. This reaction occurs when a patient receives the wrong blood type during a transfusion. Involves antibodies
Immune Complex Hypersensitivity (Type III)
elicited by antigens in vaccines, on microorganisms, or on a person’s own cells. Large antigen-antibody complexes form, precipitate on blood vessel walls, and cause tissue injury within hours. Involves antibodies
Delayed Hypersensitivity (Type IV)
triggered by exposure to foreign substances from the environment (like poison ivy), infectious disease agents, transplanted tissues, and the body’s own tissues and cells. Delayed hypersensitivity T cells react with the foreign cells or substances causing in some cases extensive tissue destruction. Cell mediated and does not involve antibodies
Primary Immunodeficiencies
genetic or developmental defects in which the person lacks T cells or B cells or has defective ones.
Secondary Immunodeficiencies
result from damage to T cells or B cells after they have developed normally
Autoimmunization
the process by which hypersensitivity to self develops. This results in the production of autoantibodies
Reasons for autoantibody production
(1) genetic factors
(2) antigenic mimicry
(3) Failure of clonal deletion
(4) mutations
(5) Viral components inserted into host cell membranes act as antigens
(6) damage to the sympathetic nervous system
Antigenic mimicry
antigens of tissue resemble antigens of some pathogens, causing the body to attack them
Failure of clonal deletion
failure to delete TH cells that recognize self antigens
Examples of Autoimmune Disorders
Myasthenia Gravis, Rheumatoid Arthritis, & Systemic Lupus Erythematosus
Autograft
grafting of tissue from one part of the body to another
Isograft
a graft between genetically identical individuals
allograft
a graft between two people who are not genetically identical
xenograft
a transplant between individuals of different animal species
major histocompatability complex (MHC)
Genes that produce a set of self antigens called histocompatability antigens
human leukocyte antigens (HLAs)
The MHC molecules that are found on human cells.
transplant rejection
when transplants at first appear healthy, but within a few weeks become inflamed and fall off. Caused by rejection by the body’s immune sytstem
HLA-DR
antigens that are known to generate the strongest rejection reactions
Graft-versus-host (GVH) disease`
when the transplanted tissue contains immunocompetent T cells that launch a cell-mediated responce against the recepient’s tissues
Difference between transplant rejection and GVH
- Transplant rejection the host rejects the transplant
- GVH the transplant rejects the host
Drug Reactions
most drug molecules are too small to act as allergens. However, if a drug combines with a protein in our body, it can act as a hapten and induce hypersensitivity. All 4 types of hypersensitivity can be triggered by drug reactions
Why does HIV interfere with the proper function of both the humoral and cell-mediated portions of the immune response?
because HIV almost exclusively attacks the lymph nodes, which are essential to all immune function.
sererology
the scientific study of plasma serum and other bodily fluids
Precipitin Test
used to detect antibodies or antigens. Based on a precipitation reaction in which antibodies called precipitins react with antigens, diffuse towards eachother, and form a visible precipitate
Precipitin Test: Agar vs Liquid
The precipitn test can be performed in both liquid and in agar, however the results that you are looking for are the same in both. and that is the presence of a precipitin band or ring which signals the presence of antibodies and antigens.
Agglutination
the clumping together of cells
antibody titer
the quantity of antibodies
Complement Fixation Test
A multistep procedure that begins with the inactivation of complement from a patient’s serum by heating. The serum is then diluted, and know quantities of known non human complement and test antigen are added. The antigen is specific to the antibody that is being tested for. The mixture is incubated to allow the antigen to react with any antibody present. Next, an indicator system typically consisting
of sheep red blood cells and antibody against those
cells are added. If the antibody to the test antigen was
present in the patient’s serum, the antigen-antibody reaction
will have fixed (combined with) the complement.
Hence the blood cells will not be lysed, and the test will
be positive, forming a red button of undamaged cells
If it was suspected that a patient had a particular microorganism in their bloodstream, what would one need to detect this organism in a sample of their blood if you want to use fluorescence microscopy?
To detect directly the presence of a specific antigen in a tissue a solution of fluorescein-tagged antibody to that antigen
is prepared, added to cells or to a thin section of tissue, incubated, and then washed. Any dye-tagged antibody that has complexed
with antigen in tissue will fluoresce when viewed by fluorescence microscopy.
Enzyme-linked immunosorbent assay (ELISA)
a modification of RIA in which the anti-antibody, instead of being radioactive, has an enzyme tag attatched to it. TO measure an antibody in a test specimen by ELISA, a known antigen is placed in plastic well plates. Some antigen molecules attach to the plastic. The antibody being measured is added and allowed to bind with the antigen. After the antibody being measured has reacted with the antigen, the anti-antibody–enzyme complex is added. Finally, a substrate that the enzyme converts to a colored product is applied. The amount of colored product is proportional to the concentration of the antibody.
Desensitization
denatured allergen is injected subcutaneously which may induce a state of tolerance, preventing the activiation of those B cells that mature into IgE secreting plasma cells. By receiving gradually increased doses of this injection, one may produce IgG antibodies called blocking antibodies, against the allergen. The number of suppressor T cells sensitized to the allergen also increase significantly during desensitization .
Blocking antibodies
these antibodies bind to the allergen before it has a chance to react with IgE, so mast cells do not release mediators.
