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28January 2006 28January 2006

28January 2006 - PDF document

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28January 2006 - PPT Presentation

antigentyping frequent agitation dissociation of without denaturing red cell membrane Some antigens may remain intact positive RBC for antigen typing Chloroquine Incubate 1 volume cells ID: 263080

antigen-typing frequent agitation

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28January 2006¥Continuing Education Topics & IssuesIntroductiontion that individuals must be able to define and un-derstand. These terms include adsorption, elution,and absorption. Adsorption is the uptake of antibodyby cells. Elution is the removal of antibody fromcells. Absorption is the removal of antibody fromAbsorption techniques have a number of uses in antigen-typing frequent agitation dissociation of without denaturing red cell membrane Some antigens may remain intact positive RBC for antigen typing Chloroquine Incubate 1 volume cells and 4 volumes chloroquine diphosphate immune complexes Requires two hour incubation Same as modified heat Continuing Education Topics & Issues ¥January 200629cells to demonstrate specificity in cases of multipleTo accurately phenotype red cells withpositive DATWhen cells are heavily coated with IgG antibod-ficult and those with antiglobulin reactive antisera arethe cell surface without damaging red cell integrityor altering antigenic reactivity. The desired end prod-uct is the red cell, not the antibody. As an example,ies other than Rh), the DAT may be positive due tobody. For example, Rh positive red cells giving astrongly positive DAT may type as Rh negative due tocontrol will both be positive. This fact can be a seri- C with agitation. Spin dissociation of denatures cell membrane Eluate stained with effective for warm auto/alloantibodies Lui Freeze-Thaw Rapid thaw at 37Spin and harvest temperature cause the dissociation by change in red cell configuration Ultrasonic ultrasonic bath one harvest eluate shearing forces from waves and thermal energy produced by sonication needs special RBC. Wash yields a hemoglobin-free glycine buffer (pH 3.0) to stroma. phosphate buffer after elution of proteins causing a change in configuration Slow process requiring autoantibodies. Decreased sensitivity for Kidd system C) glycine (pH 3.0) directly to RBC. Incubate one minute harvest eluate. Readjust pH with causing a change in structural Eluate stained with hemoglobin. Less eluting many alloantibodies and RBCs one minute. Vent, spin, and Incubate 37056residual ether membrane destroying structural lipid bilayer or may alter tertiary and explosive. Must store in refrigerator and autoantibodies. Decreased sensitivity for Anti-S/s Xylene xylene and incubate at 56 Remove xylene and stroma by vacuum aspiration. not require explosion-proof Requires vacuum aspiration and autoantibodies and chloroform. Spin nonexplosive and autoantibodies Elution Techniques 30January 2006¥Continuing Education Topics & Issuesous pitfall for the novice blood banker. Note that theD antibody is capable of causing this reaction. Toovercome this problem, a gentle heat elution or theneither of these procedures disrupts the red cells butleaves them intact where appropriate antigen typingprocedures can be performed (see table on previousElution removes antibody molecules from the redchanging conditions to favor dissociation of antibodyfrom antigen. Many techniques are available, and nopared by one technique is unsatisfactory, it may behelpful to prepare another eluate utilizing a differentThe red cells used for any elution technique mustbe thoroughly washed to remove all antibody exceptthat bound to the cells. Six washes with large volumesof saline is usually sufficient. Adequacy of washing istested by examining saline from the last wash for thepresence of antibody by the indirect antiglobulin(IAT) procedure. If antibody is detectable in the lastwash, there could be enough unbound antibody mol-the eluate are not valid. This assumes the possiblemixture of alloantibody and autoantibody.As soon as the elution is completed, remove theavoid reattachment of antibody to cell stroma and apossible false negative test result.Elution TechniquesThere are several different techniques for elutionthe antigen/antibody complex. The table below indi-cates the various techniques used, describes the pro-cedure and action, lists the advantages and disadvan-tages of each, and gives times when each methodBlaney, K, & Howard, P. (2000). Basic and Applied Conceptsof Immunohematology. St. Louis: Mosby. Brecher, M. (2002) American Association of Blood BanksTechnical Manual, 14th edition. Bethesda: AABB.Modern Blood Banking and Transfu-sion Practices, 5th edition. Philadelphia: F. A. Davis Company.Quinley, E. (1998). Immunohematology Principles and Prac-tice.Textbook of Blood Banking and Transfu-. Philadelphia: W. B. Saunders Company. Turgeon, M. (1995). Fundamentals of Immunohematology.Baltimore: Williams and Wilkins. TogetherÉMaking a WorldDental Assistants Recognition Weekexhibit throughout the year.American Medical Technologists Continuing Education Topics & Issues ¥January 200631Article Questions for STEPParticipantsAnswer questions only on the official STEP answer sheet. If you do not have the official STEP answer sheet, ayearÕs supply can be obtained (at no cost), simply by writing to: STEP Program Answer Sheets, American Med-ical Technologists, 710 Higgins Road, Park Ridge, IL 60068-5765, or by fax: 847/823-0458, or by e-mail:In the following, choose the Removal of antibody from cells is a definition of:Removal of antibody from serum is a definition of The elution procedure would be of LEASTbenefit in the determination of:diagnosis of ABO HDNcharacterization of AIHAsingle alloantibody identificationWhen the DAT is positive due to IgG sensiti-zation and the eluate shows no reactivity, thefirst thing the scientist should do would be to:consider this an inconclusive findingWhich of the following elution procedureswill leave the red cells intact so that they canThe purpose for testing the sixth wash follow-ing an elution is to assure that all: complement is removed from samplebound antibody molecules are removedremoved from sampleWhich of the following is NOT a basic technique? intervalWhich of the following elution techniques isOrganic acidsWhat results would you expect on an eluatethat had been prepared and allowed to remainin contact with the RBC for an extended period of time?. False negativeFalse positiveNo observable effectA group A Rh negative weak D negative mother with an anti-D titered at 1024 gavebirth to a baby with the following laboratoryÐ Baby blood type is group A Rh negative Ð DAT 4+ with polyspecific and monospecificWhat is the MOST likely cause of this problem?