Term
| 3 types of immunological disorders |
|
Definition
1. Hypersensitivity
2. Autoimmune disease
3. Immunodeficiency |
|
|
Term
|
Definition
| reactions to usually harmless substances are often called allergies or allergic reactions |
|
|
Term
|
Definition
| antigens that cause allergic reactions |
|
|
Term
| 4 major types of allergic reactions |
|
Definition
1. Type I: Immediate IgE-mediated
2. Type II: Cytotoxic
3. Type III: Immune complex-mediated
4. Type IV: Delayed cell-mediated |
|
|
Term
| type 1 hypersensitivity is also called? |
|
Definition
| IgE Mediated Hypersensitivity |
|
|
Term
| Mechanism of IgE mediated hypersensitivity |
|
Definition
1. 1st exposure to antigen induces IgE antibody response leading to sensitization
A) Antigen is taken up by dendritic cells (APC) & merged with MHC molecules
B) APC presents the antigen to T-cells
C) Activated T-cells release cytokines that stimulate B-cells to produce plasma cells which secrete large amounts of IgE
D) IgE antibodies bind to mast cell receptors and the individual is now “sensitized”
2. During the subsequent exposures, antigens activate IgE antibodies on the mast cell causing it to degranulate
A) Histamines, leukotrienes, prostaglandins, and/or cytokines are released
B) These chemicals are the cause of hives, hay fever, asthma & anaphylactic shock
3. Reactions occur w/in 30 mins of exposure |
|
|
Term
|
Definition
allergic skin condition characterized by formation of wheal & flare pattern
A) Frequently the result of seafood allergies
B) These reactions are due to the release of histamine which causes dilation of tiny blood vessels and the leaking of plasma into the area |
|
|
Term
|
Definition
itchy, teary eyes, sneezing, and runny nose; occurs when allergic person
inhales an antigen rather than ingests it
A) also mediated by histamine |
|
|
Term
|
Definition
inhaled allergen causes chemical mediators from IgE to stimulate increased mucus secretions & spasms of the bronchi
A) leukotrienes & prostaglandins are responsible |
|
|
Term
|
Definition
1. Antigen enters the bloodstream and becomes widespread and the reaction affects almost the entire body (systemic)
2. Loss of fluid from the blood vessels into tissues causes swelling and possibly shock
3. Reactions may be fatal within minutes
4. Bee sting, peanut, and penicillin allergies account for most cases
5. Can be controlled by epi injections |
|
|
Term
|
Definition
1. Desensitization or immunotherapy is often effective in decreasing the Type I hypersensitivity state
A) Repeated injections of very small amounts of antigen are given over several months
B) This regimen leads to the formation of specific IgG antibodies
C) The IgG reacts with antigen before it can bind to IgE & therefore it blocks the IgE reaction that might result in allergic reactions |
|
|
Term
|
Definition
A. Also called Cytotoxic Hypersensitivity because it utilizes antibodies that can destroy normal cells by complement lysis or by antibody-dependent cellular cytotoxicity (ADCC)
B. Generally occur w/in hours after exposure
C. Transfusion Reactions
D. Hemolytic Disease of the Newborn |
|
|
Term
|
Definition
the ABO blood groups are the major cause of hemolytic anemia in blood transfusion patients
1. Recall that persons with A type blood possess the A antigen and the natural antibody anti-B
2. Persons with B type blood possess the B antigen and the natural antibody anti-A
3. Persons with O type blood lack both the A and B antigens but possess both the natural antibodies anti-A and anti-B
4. Persons with AB type blood possess both the A and B antigens but posses no natural antibodies
5. In the case of ABO incompatibility, the antibodies cause reactions that include fever, low blood pressure, pain, nausea, and vomiting
6. Cross-matching the bloods & other techniques are used to ensure compatibility of donor & recipient |
|
|
Term
| Hemolytic disease of the newborn |
|
Definition
1. Also called Erythroblastosis fetalis
2. mother is Rh- & baby is Rh+
3. Upon delivery, Rh+ antigens are transferred to the mother’s bloodstream which causes her to produce anti-Rh antibodies
4. If the mother becomes pregnant again with an Rh+ child, the antibodies cross the placenta, enter the circulation of the fetus, and cause extensive fetal erythrocyte damage
5. RhoGAM may be administered to prevent this reaction
A) contains Rh antibodies & prevents mother’s natural production of them
B) widely used at 28 wks & after delivery during all susceptible pregnancies |
|
|
Term
|
Definition
A. AKA Immune Complex-Mediated Hypersensitivity
B. Occur w/in hrs or days after exposure
C. When there is a slight excess of antigen, the antigen-antibody complexes activate complements & stimulate neutrophil & basophil degranulation
1. Results in vasodilation, increased vascular permeability, & inflammation
D. Sm antigen-antibody complexes are often deposited in walls of sm blood vessels in skin, joints & kidneys where they continue to cause inflammation & eventually tissue damage
E.complexes can also precipitate causing clots to form in sm blood vessels leading to failure/death of organ
1. Known as disseminated intravascular coagulation |
|
|
Term
| examples of type 3 hypersensitivity |
|
Definition
1. Arthus reaction – localized tissue death
A) ex. Chronic Obstructive Pulmonary Disease (COPD)
2. Serum sickness – seen in individuals immunized/treated with animal serum |
|
|
Term
|
Definition
A. Also called Delayed Cell-Mediated Hypersensitivity
1. occurs within days after exposure
B. T-cells rather than antibodies are involved with this type |
|
|
Term
| examples of delayed hypersensitivity (type 4) |
|
Definition
1. Tuberculin skin test
2. Contact hypersensitivity
3. Delayed hypersensitivity to infectious disease |
|
|
Term
|
Definition
a positive test results when circulating antibodies (only present if person has been exposed) bind to the protein antigens of the tuberculosis bacteria introduced under the skin
A) peaks 2-3 days after exposure
B) the redness results mainly from sensitized T-cell reactions, the release of cytokines & the influx of macrophages to injection site
C) false positive tests can result from exposure to another species of Mycobacterium or use of BCG vaccine |
|
|
Term
|
Definition
mediated by T-cells that release cytokines when they come into contact with the same antigen
A) the cytokines cause inflammation which attracts WBC to the site
B) these then release chemicals that result in allergic/contact dermatitis
C) Ex: poison ivy, poison oak, nickel reactions, and latex reactions |
|
|
Term
| delayed hypersensitivity to infectious disease |
|
Definition
as T-cells destroy macrophages & sick body cells, tissue damage results
A) Ex: leprosy, tuberculosis, & herpes simplex infections |
|
|
Term
|
Definition
| grafts from the same person |
|
|
Term
|
Definition
| grafts donated by a genetically identical twin |
|
|
Term
|
Definition
| grafts between non-identical humans |
|
|
Term
|
Definition
| transplantation of tissue from a non-human organism |
|
|
Term
|
Definition
B. Transplantation rejection of allografts and xenografts are caused largely by Type IV cellular reaction
C. Transplant success is dictated by the similarity of the MHC antigens on the surface of human cells
1. MHC tissue typing is done to ensure no major tissue incompatibilities exist b/w patient & donor
D. Often immunosuppressive drugs are taken to reduce rejection
1. These treatments make patient susceptible to opportunistic infections |
|
|
Term
|
Definition
A. Autoimmune diseases occur when the immune system of the body responds to its own tissues as if they were foreign
B. May result from normal reactions to antigens that are similar, though not identical, to the host’s normal antigens
C. Autoimmune reactions occur over a spectrum ranging from organ-specific to widespread response not limited to any one tissue
1. Grave’s disease (thyroid) & Insulin-dependent diabetes (type 2) mellitus (pancreas) are organ specific
2. Lupus & rheumatoid arthritis are considered widespread |
|
|
Term
| treatment of autoimmune diseases |
|
Definition
1. Usually treated with immunosuppressive drugs that kill dividing T-cells and thus control the response
2. Also treated w/ drugs that interfere w/ T-cell signaling such as cyclosporin
3. Steroids & other anti-inflammatory drugs used to relieve symptoms
4. Some patients require replacement therapy (ex. insulin for diabetics)
5. Transplantation of damaged organ is a last resort |
|
|
