Presentation on theme: "Reagents and Methods for Testing in the Blood Bank"— Presentation transcript:
1 Reagents and Methods for Testing in the Blood Bank
2 Major Focus Constructed around detecting Antigens and Antibodies Historically viewed by agglutination: now includesGelSolid phaseMolecular techniquesAutomationWith the exception of molecular, they are still Antibody-Antigen reactions
3 Routine Testing Typing of the ABO and Rh Antigens Typing for Antigens of Other Blood Group SystemsAntibody ScreenAntibody IdentificationCompatibility Test (Crossmatch)Direct Antiglobulin Test
4 ABO and Rh AntiseraWhere to the Antigens come from?
5 Antibody Screen Antigens Where do the Antibodies come from?
6 Reagent cells for reverse typing Where do the Antibodies come from?
8 Principle: Antihuman globulins (AHG) from immunized animals bind to human globulins whether free in serum or attached to RBC’SIgM is so large it usually reacts at room temperature spinIgG needs a little help- a bridge molecule to agglutinate RBC’sAHG acts as a bridge molecule
9 Polyspecific vs Monospecific AHG Antibodies to both human IgG and to C3dAdvantage is that they may detect complement dependent antibodies on RBC’s (Anti-Jka)Disadvantage is it may cause more nuisance positivesMono SpecificAntibodies to Human IgG or C3d onlyMay miss some antibodies but has less nuisance positives
10 Used with all negative AHG reactions Coombs Check CellsCheck cells are added to see if AHG is present and functioning
11 This methodology is vital to blood bank testing
12 Antibody Screen (Indirect) Purpose is to detect In Vitro sensitizationDetection of unexpected AntibodyUses O cells with antigens represented on 2-3 different cells of DCEce, MNSsP, Lea Leb, Kk Fya, Fyb, Jka, Jkb.Homozygous expression of Antigens is valued over heterozygous (may show dosage effect, greater antigen density per cell the greater the sensitivityNeed to be sure to run Auto Control
14 Antibody Screen Limitations Low frequency antibodies may not be detectedAntibodies with low titers may not be detectedABO antibodies will not be detected
15 Direct Antiglobulin Test (DAT) Detects in Vivo sensitizationExamples when this would be used would be HDN, Hemolytic Anemia, Auto Immune Hemolytic Anemia (AIHA)Usually would use polyspecific AHGNeed to consider if there is in vivo hemolysisPatient recently transfusedMedicationsUnexpected Allo antibody
17 Antibody Identification Use multiple cell panels, enhancement processes and varying incubations to help identify the Antibody(ies).What you need to consider in the process isPatient Medical HistoryAntigen profile of Panel cellsResults of Auto controlWhat phase, what strength of agglutinationCrossing out procedureDoes this antibody match the reaction pattern
19 Enhancement MediaEnhancement media assists the attachment of an antibody to the specific antigen on the red cellBovine Albumin ( used during incubation)Low-Ionic Strength Saline (what commercial test cells are in)Polyethylene Glycol (concentrates Antibody)Enzymes (Ficin and Papain) Reduces negative charge. Some Antibodies are enhanced like Rh, Lewis others are destroyed like Duffy and M,N,S
20 Alternate Test Methods AutomationGel TechnologyMicroplate testingSolid Phase TestingSolid and Microplate have exactly the opposite interpretations of reactionMolecular Biology (above my pay grade)Other than Automation and Gel, these other processes are used in Donor centers or large Reference Labs.
21 Lab Assignment We will be following Procedure seen on the video We will be using manual wash for the AHG testing, this will be demonstrated for you in classTry to limit the centrifuge spin time to 20 seconds especially on the wash cycle.We need to learn a good technique on manual wash, it will mean the right result, not just any result.This project was funded at $3,000,000 (100% of its total cost) from a grant awarded under the Trade Adjustment Assistance Community College and Career Training Grants, as implemented by the U.S. Department of Labor’s Employment and Training Administration. Rogue Community College is an equal opportunity employer/program. Auxiliary aids and services, alternate form and language services are available to individuals with disabilities and limited English proficiency free of cost upon request.This work is licensed under a Creative Commons Attribution 4.0 International License.
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