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100 Cards in this Set
- Front
- Back
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What is a hypersensitivity/allergy?
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immune responses which are damaging rather than helpful to host
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Allergen
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Ag that causes allergy
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Sensitization
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after initial exposure, the system is activated to recognize the Ag
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Describe Type I hypersensitivity
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occurs immediately (within 2-30 min)
localized or systemic Involves: IgE, mas cell, basophil, eosinophil |
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What does Type I immediate hypersensitivity include
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IgE, mast cell, basophil, eosinophil
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How long does Type I take?
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2-30 min
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mast cells
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found in connective tissue of skin, respiratory tract, and in surrounding blood vessels
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Basophils
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in the blood
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Eosinophils
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mast cell degranulates and releases peptides that stimulate bone marrow to release eosinophils which produce a large amount of leukotrienes (inflammation)
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What do eosinophils produce
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leukotrienes
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What releases eosinophils
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bone marrow
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What does histamine do
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causes vessel dilation and increase3d permeability
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What is the major ingredient in asthma
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leukotrienes
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What is localized anaphylaxis?
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reaction occurs at the site where allergen enters
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Hay fever
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inhalation of pollens, fungal spores
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What occurs in localized anaphylaxis
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sensitized mast cells in upper respiratory tract release histamine which causes itchy watery eyes and runny noses
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What is treatment for localized anaphylaxis
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antihistamines
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What is asthma
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sensitized mast cells in bronchioles release leukotrienes and cause smooth muscle contraction and difficulty breating
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What is treatment for asthma
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epinephrine
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Systemic anaphylaxis
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allergen is injected into blood (or ingested) and causes vasodilation and shock
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What is treatment for systemic anaphylaxis?
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epinephrine
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What shows up in a skin test for allergies if positive
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edema
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How do you prevent type I immediate hypersensitivity
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avoid contact, immunotherapy (allergy shot), treat symptoms
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What is immunotherapy
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allergy shot (injection of small doses of allergen)
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What are possible mechanisms with immunotherapy
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induce more Th1 and less Th2 or stimulate IgG production
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how can you treat symptoms of Type I immediate hypersensitivity?
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antihistamines or epinephrine
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Epinephrine
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a hormone that can relax smooth muscles and decrease vascular permeability
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What is Type II Cytotoxic hypersensitivity
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foreign anitgen present on host cell -> Ab react w/ Ag-> death of host cell due to: C' fixation, ADCC, or phagocytes
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What are 3 ways host cell dies in Type II cytotoxic hypersensitivity?
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C fixation (MAC or inflammation)
ADCC (killer cells) Attack by phagocytes |
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What do phagocytes release
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lysosomal contents to damage hosts tissues
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What are some killer cells
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macrophage, PMN
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What is immune thrombocytopenic purpura?
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drug reaction in type II hypersensitivity in which platelets are killed
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What occurs with Type II hypersensitivity and viruses
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viral infected cells display viral antigens on host cell surface and are killed by cytotoxic reaction (or Ab-> ADCC or C' fixation)
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Why do we not have antibodies against our blood type
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clone deletion
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What is hemolytic disease of newborn
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If mother is Rh- she has no ab against Rh Ag and there is no blood exchange until birth so after the first child she has Ab against Rh Ag and IgG will move across placenta to fetus and kill it (2nd child)
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How do you prevent hemolytic disease in newborns?
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Rhogam (anti pH serum)
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When is Rhogam given?
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to Rh- pregnant woman at 28 weeks and within 72 hours after abortion, miscarriage, or childbirth
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How does Rhogam work?
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blocks Rh antigen and the mother is not exposed
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How often does a mother need a Rhogam shot?
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28 weeks and within 72 hours (each pregnancy)
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What is Rhogam
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and antibody against Rh so it blocks Rh antigen and the mother is not exposed to it and cannot make antibodies against it
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What happens with Type III hypersensitivity?
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Ag-Ab complexes are too small to be eliminated by eosinophils and they circulate freely in the blood and become trapped in organs joints and tissues and this causes complement to be fixed and causes inflammation of surrounding tissue
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How does Type III damange tissue?
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fix C' and can cause inflammation and MAC
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What happens in glomerulonephritis?
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Ag-ab complexes deposit on th ewall of the glomeruli in kidney and fix C' and causes inflammation and kidney trouble
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When can glomerulonephritis take place
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after strep throat without tx
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When does type IV hypersensitivity occur?
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12-24 hr later
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What does Type IV involve
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CMI (Tc, Th1, lymphokines, macrophages)
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What occurs in Type IV second exposure
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sensitized Tc cells attack target cells with foreign Ag, sensitized Th1 release lymphokines attracts macrophages and release lysosomal contents that damage surrounding tissue and cause inflammation
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What is an example of Type IV hypersensitivity?
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TB test: inject protein Ag (PPD) and a rash appears 48 h later if positive (CMI)
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Know page 520
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in book
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What is contact dermititis?
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may not notice 1st exposure but notice 2nd exposure: catechol in poison ivy acts like a hapten and causes CMI
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What is a graft
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tissue from a donor to recipient
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What is an isograft
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giving tissue to an identical sibling or clone
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What is an autograft
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giving tissue from one part of the same animal to another part
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What is an allograft?
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giving tissue to another member of the same species
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What is xenograft
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transplanting tissue from one species to a different species
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What type of graft has strongest rejection
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xenograft
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Where is MHC presented
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surfaces of all nucleated cells (all but RBC)
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What is MHC encoded by
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group of genes A B C Dp Dq Dr
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What are alleles?
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different versions of a gene
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Where is MHC I
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on all cells but RBC
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Where is MHC 2?
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on antigen presenting cells (macrophages and B cells)
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What happens in rejection?
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transplanting unmatched tissues or organs and they're attacked by Tc, Th1, macrophages, and NK (also Ab)
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What can rejection cause
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any type of hypersensitivity
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When does Graft versus host reaction occur?
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after one marrow transplant when the host and donor have
different MHC 1 -> graft T cells attack all host tissues different MHC 2 -> graft T cells attack all APC and causes immunosuppression and makes them susceptible to infection |
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What occurs if graft versus host have different MHC II
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graft T cells attack all APC and causes immunosuppression and makes them susceptible to infection
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What occurs if graft versus host has different MHC I
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graft T cells attack all host tissues
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What does bone marrow harvest?
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B and T cells
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What needs a perfect match
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bone marrow transplant
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What are privileged site?
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certain parts of the body not exposed to lymphocytes or parts that contain high levels of immunosuppressive molecules: grafts at these sites are not rejected by host
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What are some privileged sites?
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cornea, brain, testes
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Why are fetuses not rejected?
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MHC I AND II are not expressed by early embryos: T cells are not functional in the placenta: mothers immune system is suppressed
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What is critical in donor recipient match in blood type?
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MHC match: type MHC proteins
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What requires 100% match?
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bone marrow
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What requires 50% match or less?
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other organs
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What do you do to prevent rejection?
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corticosteroids and cytotoxic drugs, immunophilins, other lymphocyte depleting therapy
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What do corticosteroids do?
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suppress response of T cells to Ag, cytotoxicity of Tc, and inflammation
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What do cytotoxic cells do?
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blocks cell division
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What do immunophilins do?
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inhibits T cells only
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What does cycosporine do?
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suppress dividing T cells only
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What are some other lymphocyte depleting therapy?
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monoclonal ab against CD3 (on T cells)
monoclonal ab against IL-2 receptors (on activated T only) |
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What is CD3 on
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T cells
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What is IL-2 receptors on
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activated T cells
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WHat occurs in autoimmune disease?
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hosts immune system attacks hosts own tissues
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What may be involved in autoimmune disease?
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Ab and CMI
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What type hypersensitivty can autoimmune disease be?
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Type II, III, or IV
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What is the difference between type II and III hypersensitivity?
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Type II they're bound to host cell: Type III they're free circulating
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What may be some causes of autoimmune diseases?
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mother and fetus may exchange cells during preganancy and autoimmune develop later
viral infection-> changes infected cells, genetic deficit, immune response to hidden Ag, Ab against pathogen cross reaction with own Ag due to molecular mimicry, failure of normal control |
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What happens in multiple sclerosis?
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Tc attacks and destroys myelin sheath that insulate the brain and spinal cord neurons: increases speed of nerve impulses along neurons and causes deficits in vision, speech, and neuromuscular function
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What is systemic lupus erythrematosus?
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autoantibody against DNA released from dead cells and forms Ag-Ab complex and is deposited in dermis, epidermis, joints, kidneys, etc. and causes inflammation
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What type of hypersensitivity is lupus?
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type III
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What do you use to treat lupus?
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antiinflammatories
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What is rheumatoid arthritis?
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B cells in joint produce autoab against collagen in cartilage and ag-ab complexes in the joint cause inflammation
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What type of hypersensitivity is Rheumatoid arthritis?
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Type III
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What is a primary immunodeficiency?
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birth defect
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What is secondary (acquired) immunodeficiency?
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developed after birth; caused by malnutrition, infectious diseases, stress
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What is bubble boy?
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severe combined immunodeficiency disease (SCID) and has no immune system: died after bone marrow transplant due to EBV infection
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What is acquired immunodeficiency syndrome (AIDS)?
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HIV kills CD4 T cells (T helper), When CD4T cells decrease to 200 mcl causes AIDS
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What is an infection by a variety of opportunistic pathogens?
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AIDS
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What is kaposi sarcoma?
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rare cancer: not normally in healthy individuals
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What is disseminated herpes?
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covers whole body in people with AIDS
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