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C 16
Disorders in immunity
| Question | Answer |
|---|---|
| Define Hypersensitivity | an exaggerated or misdirected expression of immune responses Involves the same types of immune reactions as those at work in protective immunities e.g allergy, autoimmunity |
| Define autoimmunity | abnormal responses to self Ag |
| Which types of Hypersensitivity have immediate response | Type I Type II Type III |
| Type I hypersensitivity includes | most of common allergies |
| What characteristics encompass Type I hypersensitivity | *involves IgE* Hereditary-generalized susceptibility to allergies Age, infection, gender, and locale can determine risks organs affected differ from portal entry |
| What hypersensitivity Type involves IgE | Type I |
| What are the two mechanisms of Type I hypersens. | Sensitizing dose and Provocative dose |
| Sensitizing dose occurs.. | on first contact with allergen |
| Characteristics and cells involved in Sensitizing dose | -specific cells for the allergen involved produce IgE -IgE attaches to mast cells and basophils -no symptoms at this stage, 'priming" the immune system |
| Provocative dose occurs.. | subsequent (second) exposure with the same allergen |
| Characteristics and cells involved in Sensitizing dose | -allergen binds to IgE-mast cell complex -IgE-primed mast cells(and basophils) degranulate when stimulated by 2nd allergen exposure |
| Roles of mast cells & basophils in allergies | -ubiquitous location (CT for most organs);lungs, skin, GI, genital (targets these cells) -Cells degranulate when stimulated releasing chemical mediators -(physiological effect) Vasodialation, Bronchoconstriction -causes rash, itching, etc |
| Chemical mediators of mast cells & basophils | (type I) histamine serotonin leukotriene prostaglandins bradykinin |
| Characteristics of Histamine | -most profuse and fastest chem. med. -stimulates smooth muscle, glands, and eosinophils -response to chem depends on muscle location |
| Characteristic of Leukotriene | powerful vasconstriction substances asthmatic |
| Examples of Type I allergies | -Atopic diseases (atopy) -Systemic Anaphylaxis |
| Atopic diseases | -local allergies -hay fever:allergic rhinitis (pollens) -asthma -Atopic dermatitis:eczema -food allergy -drug allergy |
| Systemic Anaphylaxis | -systemic, explosive rxn involves sudden resp obstruction circ. collapse, can be fatal -bee stings, antibiotics or serum injections |
| Treatments of allergies | Diagnosis (skin testing) Drug (anti allergy) Desensitizing (produce IgG to block IgE) |
| Antiallergy medications | -Steroids -Cromolyn -Antihistamines -Benadryl -Singulair |
| Steroids | Block plasma cell from synthesizing IgE and its functions ex. corticosteroids |
| Cromolyn | acts on surface of mast cells to inhibit degranulation |
| Antihistamines | stops cytokines (from degranulation) from acting on target cells |
| Benadryl | blocks histamine receptor |
| Singulair | blocks leukotrience receptor (treats asthma attack in patients) |
| Desensitization treatment | Injection of allergen to induce B cells production IgG antibody to compete with IgE-mast cell. IgG binds allergens (agglutination) can't bind to IgE receptor->no rxn, no degranulation |
| Type II hyersens. involves | -IgG, IgM antibodies -complement leading to lysis -antigens involved are bound to cells (alleles/RBC) |
| What are RBC surface markers | glycoproteins |
| Agglutination test | -Tests for blood type -add anti-A and anti-B antibodies to RBC -agglutination is a + test ex. anti-B antibody shows + rxn this indicates B antigen on RBC surface-> blood type B |
| Universal Donor | Type O |
| Universal recipient | Type AB |
| Result of blood incompatibility | Hemolysis -Ab-Ag complement involved in lysis -Acute hemolytic rxn: fever, chill, fast heart beat, drop in bp, severe cases are fatal |
| How do individuals acquire anti-Rh antibodies | only those previously exposed |
| Why are Rh- mothers at higher risk for miscarriage | When a Rh- mother gives birth to a Rh+ (has Rh antigen) child the first time she is newly exposed to Rh antigens and develops anti-Rh antibodies. 2nd pregnancy to Rh+ child maternal anti-Rh (IgG) cross placenta and causes hemolysis |
| Type III hypersensitivity involves | -immune complex initiated (Ab-Ag complex) -soluble antigens -react with FREE antigens (not on cell like Type II) -blood vessel and kidney tissue |
| Type III diseases | -Arthus reaction (rxn to injection of foreign substance) -Serum sickness |
| Describe Arthus rxn | -Caused by injected antigen -localized dermal injury due to inflammed vessels -acute response to 2nd similar antigen injection -severe cases cause necrosis |
| Describe Serum sickness | -caused by injection of serum, hormones, or drugs -systemic injury -Ag-Ab complex circulates and settles into membranes -Chronic-enlarged lymph nodes, rashes, painful joints, swelling, renal dysfunction |
| Type IV Hypersensitivity involves | -Cell-mediated (delayed) rxns (primarily Tcell resonse) Ex Delayed-allergic rxns and Tissue rejection |
| Delayed-allergic reactions | -Infectious allergy: TB infections elicit T cell response (basis of TB test, 24-36 hr) -Contact dermatitis: poison ivy, latex, heavy metals (skin sens.) |
| Tissue rejection | reaction of cytotoxic T cell against foreign cells of a graft recognizes noncompatible MHCI receptor week to month after graft |
| Types of tissue rejection | -Host rejection of graft: host T cells attack donor -Graft rejection of host: (GVHD graft vs host disease) donor Tc cells in in bone marrow (passenger lymphocytes) attack recipient tissue |
| Autoimmunity involves which Hypresensitivities | Type II, III, and IV |
| Autoantibodies | IgG IgM IgA immune system looses tolerance to self molecules and forms autoantibodies and sensitized T cells against self tissues |
| Systemic autoimmunities | Systemic lupus erythematosus Rheumatoid arthritis |
| Endocrine autoimmunities | -Thyroid: Graves disease: over stimulate thyroxin production Hashimoto thyroiditis: lowered production of thyroxin -Pancreas: Diabetes emllitus (type I)-damages pancreatic tissue, lower insulin production |
| Myasthenia gravis | neuromuscular autoimmunity attacks acetylcholine receptor on muscle cells paralysis |
| Multiple sclerosis | neuromuscular autoimmunity myeline sheath of neuron is damaged |
| Rheumatic fever | autoimmune disease heart valve damage from antibodies produced against group A strep (S.pyogenes) infection cross reactive antibody |
| Effects of Epinephrin | rapidly constricts blood vessels relaxes muscles in airway and lungs reverses swelling stimulates heartbeat reversing most dangerous affects of anaphylactic rxn |
| What type of blood should an O- individual receive | O- because type O has both antibodies A and B that will react with all other blood types antigens |
| What passive immunity is give to Rh- mother and what type of antibody does it have | RhoGam contains antibodies (IgD) against Rh factor |
| What type of antibodies are involved in Type III hypersensitivity | IgG and IgM |
| Characteristics of type III diseases | require sensitization and preformed AB symptoms are delayed |
Created by:
astapl01
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