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Cards In This Set
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What subdivision is the Complement system part of?
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The innate immune system
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What are the three functions of the complement system
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1. Kill pathogens2. Regulate immune complexes3. Link innate & adaptive immunity
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Three end results of the complement system
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1. Opsonization & phagocytosis2. Chemotaxis (C3a & C5a)3. Formation of Membrane Attack Complex
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Symptoms of C3 deficiency
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1. Recurrent pyogenic infections2. No C3 or complement hemolytic activity in blood3. In ability to show long-term immunity on vaccination4. Severe immunocompromisation
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3 Complement pathways & what activates them
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1. Classical - Bound Igs & CRP2. Lectin - pathogen polysaccharides or patterns3. Alternative - any surface where C3(H2O) can opsonize
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Central component of the Complement System
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C3
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Where are most complement protein produced?
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Liver (90% of them)
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Where are complement proteins located
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Body fluids and tissues
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Steps in Classical Complement Pathway up to C5
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1. C1qrs binds to Antibodies attached to their antigen2. C4 cleaved by C1s to C4b and C4a3. C4b if close to membrane or antigen it opsonizes4. Opsonized C4b cleaves C2 to C2b & C2a5. C4b binds C2a = C3 Convertase (C3C)6. C3C cleaves C3 to C3b & C3a7. C3b if close enough to membrane opsonizes8. C3b also binds to C3C = C5 Convertase (C5C)
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Which Immunoglobulins can activate complement
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IgG1, IgG2, IgG3, IgM, IgA1, IgA2
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What can C1 bind
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1. Antibodies2. Cell wall & membrane protein of lots of pathogens3. Fragments membranes, modified proteins, & phospholipids4. CRP & serum amyloid P
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If C1q is lost what would happen
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1. Recurrent bacterial infections2. Systemic Lupus Erythromatosis
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What does C-Reactive Protein recognize
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Phosphocholine of bacteria and apoptotic cells
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Steps in Lectin Complement Pathway up to C5
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1. Binding of Mannose Binding Lectins (MBL) or Ficolins to pathogen sugars (Similar to C1qrs)2. MASP-2 cleaves C4 to C4b & C4 a3. If close C4b opsonizes to membrane4. Opsonized C4b cleaves C2 to C2b & C2a5. C2b binds to C4b = C3 Convertase (C3C)6. C3C cleaves C3 to C3b and C3a7. If close to membrane C3b opsonizes8. C3b also binds to C3C = C5 Convertase (C5C)
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If Mannose Binding Lectin was lost what would happen
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Susceptibility to bacterial infection (especially baby)
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