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103 Cards in this Set
- Front
- Back
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What is atopy?
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Atopy is any type of allergic reaction found on the skin.
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What is anaphylaxis?
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An allergic reaction that is systemic and can be life threatening...usually respiratory.
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Give the major food allergens
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Fish
Peanut Eggs Shellfish Soy Milk |
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T or F: Only select tissues in the body can be affected by drug reactions
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FALSE. Depending on the allergen, route of entry, transmission, and individual sensitivies, virtually all tissues on the body can be affected.
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What are the two types of anaphylaxis?
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Systemic (respiratory/circulatory)
Cutaneous (wheal and flare reaction) |
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How does hyposensitization occur and what are two theories surrounding its mechanism?
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Hypsensitization prevents reactions between allergens, IgE, and mast cells by:
1. injecting allergens to introduce high levels of IgG which blocks or removes allergens before they come in contact with IgE. 2. It is possible that allergen delivered combines with IgE and takes it from circulation before it can react with mast cells |
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Are Type I hypersensitivities predisposed or acquired?
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Predisposed (inherited)
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What are the portals for Type I?
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Skin
Respiratory tract GI tract |
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What are the inflammatory mediators?
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Heparin
Histamine Bradykinin Leukotriene Platelet-activating Prostaglandins Seratonin |
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Which cytokine is known as "slow-reacting substance" of anaphylaxis?
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Leukotriene
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What are the 4 types of hypersensitivity?
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1. Immediate
2. Antibody 3. Immune complex 4. T-cell mediated |
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Which of the types of hypersensitivity are B-cell mediated?
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Immediate
Antibody Immune complex |
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Which two cytokines are responsible for the wheal and flare reaction?
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Platelet-activating
Histamine |
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What are prostaglandins most widely known for?
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Contraction of uterus during delivery, vasodilation
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What is the significance of Bradykinin
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Blood clotting, chemotaxis, increased mucous secretion
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Explain how a drug reaction occurs
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It is not actually the intact drug that causes the allergic reaction but the hapten given off by the liver breaking down or processing the drug.
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What is the provocative dose?
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The dose that provokes possible reaction (after the first--sensitizing--dose)
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What is the sensitizing dose?
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The first dose(s) of an allergen, does not produce a reaction
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Where are mast cells located? Basophils?
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M--Connective tissue
B--Circulating in blood, migrate into tissues |
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What is the mechanism of action of seratonin?
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Deminishes CNS activity
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What are prostaglandins most widely known for?
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Contraction of uterus during delivery, vasodilation
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What causes damage in an allergic reaction?
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Granulocytes because the contain enzymes the break open and destroy cells
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What is a symptom caused by vasodilation?
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Neuritis-->Headache
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What does leukotriene cause?
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Bronchoconstriction after degranulation
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What are cytokines involved in?
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Inflammatory reactions
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What is the pathway of the Sensitization part of Type one allergic response? Subsequent exposure/provocative dose?
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SENSITIZATION
1. Allergen particles enter 2. Lymphatic vessel carries them to lymph node 3. B cell recognizes with help of T cell 4. Proliferates into plasma cells 5. Synthesizes IgE 6. IgE binds to mast cell surface receptors PROVOCATIVE DOSE 7. Allergen is encountered again 8. Allergen attaches to IgE on mast cells and triggers degranulation and release of allergic mediators (cytokines) 9. Systemic distribution of mediators in blood 10. Symptoms apparent |
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What is the capacity of mast cells and basophils in regard to binding to IgE during sensitization?
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Each cell carries 30,000-100,000 cell receptors that bind to 10,000 to 40,000 IgE antibodies
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What do cytoplasmic granules contain?
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Cytokines
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What is the target organ of Histamines?
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smooth muscle (stimulation in bronchioles and intestines; relaxes in arterioles and venules)
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What are Type II hypersensitivities?
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Reactions that lyse foreign cells
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Why is IgE unique?
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It has an Fc region with great affinity for mast cells and basophils.
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How does degranulation occur in regard to mast cells and basophils?
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They release the contents of granules into the tissues when triggered by a specific allergen through the IgE bound to them.
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List three ways for allergy therapy
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Antihistimines
Epinephrine Desensitization |
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RBC's of type B have an enzyme that adds what?
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D-galactose
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RBC's of type AB contain
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both enzymes
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RBC's of type A contains and enzyme that adds what?
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N-acetylgalactosamine
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Which cell plays an important role in graft rejection?
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T-cells
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What are two potential reactions in tranplantation?
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1. Host's T-cells attach transplant donor's tissues and destroy the transplant or graft
2. Donor's T-cells recognize the host tissue as foreign and destroy it. |
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What are the different classes of grafts?
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AUTOGRAFT--tissue transplanted from one site of an individual to another (on same individual)
ISOGRAFT--tissue from identical twin is used ALLOGRAFT--most common, exchange between genetically different individuals in same species XENOGRAFT--tissue exchange between individuals of different species (only experiemental or temporary thus far) |
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What are ways graft rejection can be avoided or risk can be lessened?
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Mixed Lymphocyte Reaction (MLR)
Tissue Typing |
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What is Mixed Lymphocyte Reaction (MLR)?
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Lymphocytes of the donor and host are mixed and incubated. If compatibility exists, some of the cells will become activated and proliferate.
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What is Tissue typing?
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Similar to blood typing. Specific antisera are used to disclose the HLA antigens on surface of lymphocytes. In all grafts except bone marrow transplants, the ABO blood types must also be matched.
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Is any amount of incompatibility ever tolerable in transplantation?
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Yes. A small amount of incompatibility is tolerable in certain grafts (liver, heart, and kidney), although the closest match is sought for success.
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How many transplants occur each year in the US?
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More than 25,000
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What is the average cost of bone marrow transplants?
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$400,000--pays for search for a compatible donor and testing required.
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Describe the procedure of a bone marrow transplant
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Between 500-800mls of bone marrow are extracted from the favorable site (usually the crest and spine of the ilium--of the pelvis). The marrow is then dripped intravenously into circulation and the new cells automatically settle in the appropriate marrow regions.
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What is the mechanism of Type III (Immune complex) reactions?
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Immune complex diseases occur when an overabundance of Ab-Ag complexes force deposits in the basement membrane of epithelial tissues and become inaccessible.
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Name 3 important points regarding ABO blood types.
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1. They are named for the dominant antigen
2. The RBC's of type O lack the A and B antigens but do have other types of antigens 3. Tissues other than RBC's carry A and B antigens |
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What accounts for immediate and intense transfusion reactions?
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Preformed antibodies...Even though an individual does not normally produce antibodies in response to his/her own RBC antigens, the serum can contain antibodies that react with blood of another antigenic type, even though contact wiht this blood type has never occured.
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Describe ABO blood groups in regard to the antibodies they contain
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Type A (anti-b) contains antibodies that react with B antigen. Type B (anti-a) contains antibodies that react with A antigen
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What blood type type is considered the universal donor?
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Type O (both antigens)
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What blood type is considered the univeral recipient?
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Type AB (no antigens)
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What does the resultant destruction of RBCs lead to?
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systemic shock
kidney failure (blockage of glomeruli) Fever Anemia Jaundice Death |
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What is Rh factor named after?
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The rhesus monkey
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What percentage of the population contains Rh factor? What percentage does not?
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85%
15% |
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What are the only ways one can develop antibodies against Rh factor?
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Placental sensitization
Transfusion |
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When does the potential sinsitization for Rh occur?
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When a mother is Rh- and her fetus is Rh+
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Why is the first Rh+ child not affected by Rh?
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Because the process begins so late in pregnancy that the child is born before maternal sensitization is complete.
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What is hemolytic disease of the newborn (HDN) ofr erythroblastosis fetalis?
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The outcome of the maternal anti-Rh antibodies crossing the placenta into fetal circulation, where they affix to the fetal RBC's and cause complement-mediated lysis.
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What is RhoGAM and when is it used?
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An antiserum injected at 28-32 weeks and again immediately after delivery that keeps the maternal immune system from recognizing fetal RBCs that have escaped into the mother's circulation.
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How does graft rejection occur?
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When donor tissue (a graft) displays surface molecules of a different MHC class, the T cells of the recipient (host) will recognize its foreignness and react against it
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Graft incompatibility is a two-way phenomenon. Why?
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The graft can reject the host (especially bone marrow), and the host can reject the graft.
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Name the 4 classifications of grafts
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Autograft
Isograft Allograft Xenograft |
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What is Graft versus host disease (GVHD)?
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Occurs within 100 to 300 days of the graft, happens because the grafted tissues contain an indigenous population called passenger lymphocytes. Effects are widely systemic and toxic.
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Which type of graft is the most common?
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Allograft
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What is the most common symptom of GVHD? What other organs are affected?
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Papular, peeling skin rash is most common.
Other organs affected are the liver intestine muscles mucous membranes |
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What is the sequestered antigen theory?
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It explains that during embryonic growth,, some tissues are immunologically privileged. (they are sequestered behind anatomical barriers and cannot be scanned by the immune system).
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Give some examples of sites that act as barriers in the sequestered antigen theory
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Regions of the CNS
Lens of the eye Antigens in the thyroid and testes |
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What is the theory of immune deficiency
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Mutations in the receptor genes of some lymphocytes render them reactive to self or that a general breakdown in the normal T-suppressor function sets the scene for inappropriate immune responses.
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Explain Molecular mimicry
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Microbial antigens bear molecular determinants similar to normal human cells. Infection could cause formation of antibodies that can cross-react with tissues.
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What is the characteristic of Systemic Lupus erythematosus?
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A butterfly-shaped rash that drapes across the nose and cheeks
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What organs are involved (symptomatic)
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Kidneys
Bone Marrow Skin Nervous system Joints Muscles Heart GI tract |
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Explain the pathway of the disease lupus
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Autoantibody-autoantigen complexes appear to be deposited in the basement membranes of various organs. Etiology is still a puzzle. Viral infection or loss of T-cell suppressor function is suspected
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Who are the most affect population?
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Women of childbearing years account for 90% (indicates hormones may be involved)
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What is Rheumatoid arthritis?
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A systmeic autoimmune discease, incurs progressive, debilitiating damage to the joints.
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What organs or regions other than the joints may be affected by Rheumatoid arthritis?
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Lungs
Skin Eye Nervous System |
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How is Multiple sclerosis treated?
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*Passively with monoclonal antibodies that targe T-cells, and a vaccine containing the myelin protein.
*Symptoms can be treated with immunosuppressants such as cortisone and interferon beta |
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What is Type I Diabetes (Mellitus) caused by?
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A dysfunction in insulin production by beta cells in the pancreas or its utilization by cells
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What is Type I diabetes possibly linked to?
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Infection by the Coxsackievirus, a common cause of colds and enteric infections in a possible case of molecular mimicry
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What is MS possibly linked to?
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Associated with Epstien-Barr virus; new evidence indicates that an endogenous retrovirus may be involved.
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Give examples of Type I, II, III, and IV hypersensitivities.
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Type I--Hayfever, nut allergies, mold allergies
Type II--Rh sensitivities, Erythroblastosis fetalis (Hemolytic disease of the newborn) Type III--Arthus Reaction, Serum Sickness Type IV--Contact Dermatitis, Tuberculosis |
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What are some prime examples of Autoimmune diseases?
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Rheumatoid Arthritis
Multiple Sclerosis (neuromuscular) Systemic Lupus Erythematosus Graves Disease & Myesthenia Gravis (Endocrine) |
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What is the mechanism of action of Type II hypersensitivity?
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Complement leading to lysis of foreign cells (as in ABO groups, Rh factor)
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Explain the idea behind ABO blood groups
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A--contains A antigens, B antibodies
B--contains B antigens, A antibodies AB--contains both A & B antigens, no antibodies O--contains no antigens, but both A & B antibodies |
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A type blood contains what sugar group? B type?
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N-acetylgalactosamine
D-galactose |
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Describe Arthus Reaction
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Acute response to a 2nd injection of vaccines (boosters) or drugs at the same site as the first. Within hours, area becomes red, hot to touch, swollen, painful. Tissues are destroyed in and around blood vessels histamine is relased. Usually self-limiting.
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Describe Serum Sickness
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Named for a condition that appeared in soldiers after repeated injections of horse serum to treat tetanus. Immune complexes enter circulation; are carried throughout the body; eventually deposited in blood vessels of kidney, heart, skin, and joints. Results in enlarged lymph nodes, rashes, painful joints, swelling, fever, and renal dysfunction
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What does immune "complex" mean?
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A complex consists of an antibody (Ab) and antigen (Ag) together
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How is Hemolytic Disease of the newborn prevented?
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Passive prevention through administration of anti-Rh antibodies late in pregnancy and immediately after birth
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How does host rejection of graft occur
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T cells of a host recognize foreign class I MHC markers on grafted cells, relase interleukin-2. Cytotoxic cells bind to the grafted tissue and secrete lymphokines that begin rejection within 2 weeks of graft.
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What are the major organs where immune complexes are deposited
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Blood vessels
Heart/Lungs Joints Skin Kidney |
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Name some autoimmunities of endocrine system
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Graves Disease
Diabetes Mellitus Myesthenia Gravis Hoshimoto Thyroiditis |
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Name some neuromuscular autoimmune disease
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Multiple Sclerosis
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Name the systemic autoimmunities
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Rheumatoid Arthritis
Systemic Lupus Erythematosus |
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What is molecular mimicry? Name some autoimmune diseases that appear to be caused by molecular mimicry
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Microbial antigens bear molecular determinants similar to normal human cells
Rheumatic fever Psoriasis |
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What type of hypersensitivity is multiple sclerosis (MS)?
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Type II or IV
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What are the four portals of allergen entry?
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Inhalants
Ingestants Injectants Contactants |
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What exactly occurs during a provactive dose?
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The same allergen comes in subsequent contact and binds with the IgE-mast cell complex
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What is an example of a skin response to allergens in Type IV?
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Tuberculin reaction (delayed-response hypersensitivity)
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T or F: Only a select few organs can be successfully transplated.
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False. All major organs can be successfully transplanted.
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Allografts require what before graft is performed? How is rejection controlled?
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Tissue matching; rejection is controlled through drug administration
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Which cytokine compiments histmine?
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Seratonin
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What are the target organs of histimine?
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Smooth muscle
GI tract Skin Glands (salivary, lacrimal, mucous, and gastric) |
