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44 Cards in this Set
- Front
- Back
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IgG
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-150,000 MW
-highest serum conc -transported across placenta via Fc -four subclasses -monomeric in form |
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IgA
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-dimer, monomer
-2 subtypes -in secretions -dimeric form has J chain |
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IgM
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-pentameric form
-primary response; role in lab dx -does not pass placenta -effective agglutinator |
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IgE
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-extra constant region domain
-lowest serum concentration -binds to mast cells via Fc-allergic rxns -protection- parasitic infxs |
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IgD
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-low concentration in serum
-function largely unknown- may act as antigen receptor for B cells -no clinical meed to measure |
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AB-antigen interactions
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-binding is dynamic
-not covalent -specificity is relative, not absolute -AB binding site-forming cleft b/t heavy and light chains -antigen binding site- small; epitope; sequential vs. conformational (epitopes next to each other in folded protein) |
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immunogenity
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-how well an antigen stimulates Ab production
-foreigness- further away from human the more immunogenic it is -molecular size- larger is better -chemical complexity -genetics -route of antigen exposure |
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outcomes to antigen-antibody binding
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-agglutinates A
-activates complement -cleared/killed by phagocytic system -initiates immune response: cellular and humoral |
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afferent arm
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-phagocytic cells & other antigen processing cells located throughout the entire body
-process for main cells of the immune system lymphocytes |
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central arm
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-where gearing up and cell-cell interactions occur
-lymphocytes are main cellular component |
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efferent arm
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-humoral: plasma cells, ab specific, complement
-cellular: cytotoxic cells- specific, NK cells, macrophages |
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primary immune response
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-interactions and generation of afferent, central, & efferent arms of B and T cell system
-cytotoxic cells: fungal, parasitic, virally infected cells -humoral: bacterial |
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secondary response
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-faster, higher, longer
-lab testing (IgM first, IgG second) -vaccines vs. passive |
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3 classes of immune system diseases
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1. immune system misregulation in excess: autoimmune
2. immune system deficiency 3. immune system becomes malignant (leukemia) |
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type I hypersensitivity
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-immediate hypersensitivity, allergic, atopic rxns
-cause: overproduction of IgE, due to lack of adequate suppression -fast, mediated by histamine: contraction of smooth muscles, dilation of blood vessels, inc capillary permeability -inc in secretions, itching -extreme: anaphylaxis-systemic injection of allergen in sensitized indiv |
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allergy desensitization
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-build up other classes IgG, IgA, etc
-elimination before reaching mast cell |
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type I hypersensitivity: lab diagnosis
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-skin tests
-total IgE -specific IgE levels |
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type II hypersensitivity
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Ab dependent cytotoxic rxns
-direct via complement lysis -indirect via NK and phagocytic cells -excellent against bacteria, viral infected cells -diseases: transfusion rxns, AI hemolytic anemia, drug induced hemolytic anemia, hemolytic disease of the newborn |
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type III hypersensitivity
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-immune complexes deposited in tissue: high P regions, tubulence, filtration areas
-conditions: persistent infx, AI, chronic exposure to specific Ag |
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type III hypersensitivity exampels
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-poststreptococcal glomerulonephritis: may occur 7-14 days after pharyngeal or skin infx
-farmers lung, mushroom workers lung, cheese workers lung- inhaled chronic exposure to inhaled mold |
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type IV hypersensitivity
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-mediated by sensitized T cells- not Ab like types I-III, V
-must have prior sensitization -T cell and monocytic infiltrate to site of Ag -eczema, poison ivy, metal -lab tests: bioassays/delayed type skin tests |
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type V hypersensitivity
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-Ab stimulating/blocking rxns
-hyperthyroid -hypothyroid: Hashimoto's diease |
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Antigen Detection assays
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-culture: gold standard
-specific antigen detection: limited clinical utility and use with a few expectations (PCR) |
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PCR
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-implications for tx- HIV viral load studies
-rapid (relatively)- implications for pt treatment and cost containment -more sensitive/specific - chlamydia |
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Agg,. ELISA, RIA
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-latex agglutination: simple slide test, sensitivity less than ideal
-capture ELISA- alteration of standard Ab EIA technology: for infectious diseases -RIA- rapidly falling into disuse |
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AB detection assays
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-indirect evidence- Ab detection can only indicate exposure status, rarely by itself diagnostic
-test predictive value of disease absolutely dependent on clinical skills of physician -polyvalent vs. separate IgG/IgM -acute vs. covalescent specimens |
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Fluorescence assays
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-indirect (use secondary AB with tag) vs. direct
-problems: subjective scoring; microscope set-up very impt (transmitted light, epi** (more sensitive), bulb type, bulb life) -advantages: simple, ideal for low vol -disadvant: subjective, need expertise, not good for high vol |
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Hemagglutination assay
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-must control for RBC Ags
-antigens attached via tannic acid, chromic chloride, gluteraldehyde -generally fast 1-2hrs |
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Latex agglutination assays
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-simpler, agglutination due to unrelated ABs
-faster 1-5 min -not often used in infectious diseases |
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AB dectection assays- advantages and disasvant
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-advant: quick
-disadvant: prozone can occur, Ag-Ab system must not be univalent |
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ELISA HIV
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Add patient sera to ELISA plate
Incubate Wash Add enzyme labeled anti-Human Immunoglobulin and incubate Wash Add Substrate Incubate Add Stop acid solution and read OD on instrument -second gen tests for I.D. serologies |
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Immunoblotting/ Western Blots
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-confirmatory test
-all of the organisms proteins are separated by electrophoresis and transferred to nitrocelluose strips -pts ABs bind to individual proteins and visualized via ELISA -advant: elucidate exact specificity of Ab reactivity, eliminate false positives due to cross reactive ABs -disadvan" complex and hard to interpret, poor performace in proficiency testing, subjective |
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Immunofixation
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-electrophoresis on thin layer agarose followed antisera overlay resultign in ppt which is strained with prot stain
-prozone can and often does occur due to extremely thin agar -easy to read, minimal training required |
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Nephelometry
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1. Endpoint:
-background interference must be subtracted -sensitivity limited -longer analysis time 2. Rate: -less sensitive to background interference -inc sensitivity -short analysis time -higher purity reagents required |
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systemic autoimmune diseases
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-systemic lupus erythematosus, Sjogrens syndrome, rheumatoid arthritis, mixed connective tissue disease
-highly variable -dx: mostly clinical, lab tests |
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systemic autoimmune disease testing
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-anti nuclear antibodies (ANA): screen for many AI diseases; many autoabs detected, specific ABs rarely identified, low specificity
-methods: IFA |
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disease associated with ANA positivity
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1. connective tissue diseases: SLE< RA, vasculities
2. Infectious diseases: mono, hepatitis 3. Neoplastic disease: leukemia, solid tumors 4. Others |
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Indirect immunofluorescent assay (IFA)
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-cell line substrate
-advant: good screen: pattern gives indication of disease possiblities for clinician directed reflex testing -disadvant: high learning curve, subjective, cannot follow disease course with titer |
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ENA & Specific autoantigens
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-ABs to most of these give rise to positive ANA
-algorithim for ANA testing |
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Primary Immunodeficiencies
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-inherent defect in the immune system
-most often congenital -may have genetic component -rare (slides 102-104) |
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secondary immunodeficiencies
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-very common
-secondary to primary disease: starvation, burns, viral, bacterial -may effect all arms of immune systme |
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complement assessment
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-basic assessment: total functional complement; C3 and C4 quantitaion
-secondary assessment: Functional and quantitations of individual components (C1q, C2, ) |
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granulocyte/phagocytic assessment
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Basic assessment
-White blood cell count (WBC) with differential Secondary assessment -Oxidative burst test: Flow --Cytometry, NBT, -Chemiluminescence Chemotactic response (Migration tests) Cell adhesion molecules (Flow cytometry) (CD11a, CD18), Absolute percentage and functional up regulation - Leukocyte Adhesion molecule deficiency |
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slide 112
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slide 112
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