CLS 1113 Introduction to Clinical Laboratory Practices

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CLS 1113Introduction to Clinical Laboratory
Practices

• Unit 5
• Chapter 9
• Agglutination

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Agglutination

• The aggregation of particulate matter with a
  specific antibody.
• Two stage process
• Sensitization
• Affinity, Avidity, Ig Class
• Lattice formation
• Temperature, pH, Ionic strength

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Blood Bank

• Agglutination is the main serological process
  employed.
• Patient Red Blood Cells (RBC)
• A, B, A B, or NO ABO antigens
• Patient Serum or Plasma
• Anti-A, Anti-B, Anti-A,B or No ABO antibodies
  depending on what antigens are present on their
  RBCs

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Blood Bank

• ABO testing
• Forward Grouping Test patient red blood cells
  with known Reagent Antibody - Anti-A and Anti-B
• Reverse (Confirmatory) Testing Test patient
  serum (plasma) with know Reagent Red Blood Cells
  - A1 Cells and B Cells

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Patient Cells Patient Cells Patient Serum Patient Serum
Pt. Anti-A Anti-B A Cells B Cells Interpret
1 4 0 0 4 A
2 0 4 4 0 B
3 4 4 0 0 AB
4 0 0 4 4 O
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Agglutination

• Direct Agglutination
• Passive Agglutination
• Agglutination Inhibition

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Agglutination

• Originally, only red cells were used as a
  carrier.
• Latex beads
• Polystyrene
• Charcoal

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False Positives and False Negatives

• False Positives
• Contaminated Glass
• Autoagglutination
• A heterophile antibody
• Added the wrong antibody
• Added the wrong antigen

• False Negatives
• Not washing the test
• Inactive/outdated reagents
• Incorrect incubation temperature
• Incorrect test time
• Prozone or Postzone
• Failure to add reagents

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Antihuman Globulin Testing
Antihuman Globulin Antibody specific to human
antibodies (immunoglobulins)

• Direct Antiglobulin Test (DAT)
• Detect in vivo attachment of Ab or C to red
  blood cells

• Indirect Antiglobulin Test (IAT)
• Detect unexpected Abs in patient
• Detect specific blood group Ags

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Quality Assurance and Quality Control

• Quality Assurance
• Overall system wide quality process or program
  that includes personnel, equipment, process
  control (QC), documents and records, etc.
• Quality Control
• Monitoring a test system to determine if
  performance is within the established range of
  acceptability.