lecture 17 - Lecture 17 types III and IV hypersensitivities...

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1 Lecture 17 types III and IV hypersensitivities
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2 update Problem set due today Will go over answers next Tuesday-bring original multiple choice to class with your answers marked
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3 Sensitization- IgG antibody against cell surface molecules is induced or transferred by passive immunity IgG antibodies to cell surface molecules +/- complement Outcomes Destruction of target cells Opsonization Lysis by MAC Type 2 Hypersensitivity - Cells are targets Examples Antibodies against blood groups (transfusion reactions, Rh disease of newborn) Autoimmune diseases
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4 Type III hypersensitivity reactions are caused by immune complexes formed from IgG and soluble antigens Antigen binding to specific antibody forms a complex – immune complex-with pathological consequences Also called “immune complex disease”– examples “Serum sickness” Farmer’s lung and other occupational diseases
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5 immune complexes are different in size and form Can also occur with monovalent Ag
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6 Clearance of immune complexes from blood occurs normally C3b and C4b can bind to immune complexes in blood CR1 on RBC binds C3b and C4b RBC play a large role in spleen and liver for removal of immune complexes from the blood via CR1 receptors If ag-ab are in antigen excess zone - antigen excess complexes are not cleared easily – remain circulating and get stuck at tissue sites Genetic variations in C4b leads to increased immune complex “disease” C4b also
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7 Generalized Immune complex disease (systemic immune complex disease occurs under special conditions Serum sickness - Large intravenous dose of “antigen” Example: IV administration of antibiotics (case 35) immune serum from horses or monoclonal antibodies (mouse abs) Large dose of inhaled antigen
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8 Serum sickness Model Immune complexes clearing 9 5 Ab starts Immune complexes not cleared
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lecture 17 - Lecture 17 types III and IV hypersensitivities...

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