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35 Cards in this Set
- Front
- Back
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Define immunohematology
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Study of blood group antigens and antibodies; area of the lab that is concerned with testing patients for compatibility with blood products and the preparation of the products
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Patients who have received several platelet transfusions can form antibodies against what antigens?
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HLA (human leukocyte antigens)
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Define refractoriness.
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Poor platelet response following a transfusion
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What testing applications can be performed with HLAs?
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Paternity testing, organ and tissue transplants, platelet matching, bone marrow and stem cell transplants, increased or decreased rate of particular diseases
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What test can be ran to determine the compatibility of HLA antigens and antibodies in organ and tissue transplants?
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Lymphocytotoxicity test
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Describe the principle of the lymphocytotoxicity test.
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Dye is injected into donor and recipient lymphocytes and then the lymphocyte populations are mixed together. If the cell populations are compatible, they will not elicit an immune response against each other and no change will be seen. If, however, the populations are not compatible, they will mount a response against each other, and the cells will lyse, releasing their internal dyes. A color change will be observed from this release of dye.
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Neonatal alloimmune thrombocytopenia is caused by:
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Maternal antibodies attacking fetal cells that were inherited from the father
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Posttransfusion purpura is caused by:
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Platelet antibodies from the donor attacking the recipient's platelet antigens
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A positive reaction between antigens and antibodies can be observed by ____ or _____.
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Hemolysis or agglutination
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What are the two steps of hemagglutination?
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Sensitization and lattice formation
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Sensitization can be affected by:
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Serum-to-cell ratio, pH, temperature, ionic strength
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In a hypertonic solution, there is more sodium outside of the cell than inside. This will result in a cell that appears ____
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Crenated
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In an isotonic solution, red blood cells will appear
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Normal
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In a hypotonic solution, there is less sodium outside of the cell than inside. This will results in a cell that appears _____.
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Enlarged or ruptured
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Lattice formation is dependent on:
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Distance between cells, concentration of red cells and antisera, centrifugation
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The amount of repulsion that red cells have against each other:
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Zeta potential
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A reaction that contains many small clumps and a cloudy background is graded at
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1+
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A reaction that contains several small- to medium-sized clumps and possible cloudy background
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2+
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A reaction that contains a few large agglutinates in a clear background
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3+
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A reaction that contains one solid large agglutinate in a clear background
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4+
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AHG reagent will bind to:
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IgG antibodies and/or complement components present in a sample
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What is the crucial and most important step in testing with AHG reagent?
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Washing
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Polyclonal AHG will react with
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IgG antibodies AND complement
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Monoclonal AHG will react with
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IgG antibodies OR complement
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Indirect antiglobulin tests determine
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If a reaction COULD occur (in vitro)
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Direct antiglobulin tests determine
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If a reaction HAS occurred (in vivo)
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What are some sources of false-negative reactions in the AHG phase of testing?
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Improper washing, delayed or interrupted testing, failure to add AHG, improper cell suspension, undercentrifugation, reagent degradation, failure to notice weak positive reactions
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False-positive results in the AHG phase of testing can result from:
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Previously-agglutinated red cells, overcentrifugation, dirty glassware
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In vivo means:
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Something is performed or occurs inside the body
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In vitro means:
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Something is performed or occurs outside of the body
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A reagent that enhances the reaction between antigen and antibody is called:
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Potentiator
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What three proteolytic enzymes are used in the lab?
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Ficin, bromelin, papain
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The main purpose to test with proteolytic enzymes is to:
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Differentiate between potential antibodies a patient has by either enhancing the reaction or denaturing the epitope
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Blood groups that will be enhanced by enzymes:
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Rh, Kidd, Lewis, I, P
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Blood groups that will be denatured by enzymes:
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Duffy, M, N, S, Xg
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