What is the racial classification

							 Chapter 12

Forensic Serology
        What is serology?
• A range of laboratory tests using
  antigens and antibodies


                       Antibody
Antigens are cell membrane proteins
                   Blood
• Cells
  – Red blood cells (RBCs, erythrocytes)
  – White blood cells (WBCs, leukocytes)
  – Platelets
• Proteins
  – Enzymes
• Plasma (watery fluid)
           Red blood cells
• Antigen systems
  – A-B-O
  – Rh factor
Blood serum
• Antibodies
  – Proteins which bind to specific antigens
• Antiserum – serum containing Ab(s) that
  react against (bind to) specific antigens
• Agglutination – clumping of RBCs by
  reaction (binding) to antibodies
Blood type, antigens and serum
                 Serology
• Blood typing
  – Identifying A-B-O type with known
    antiserum (by agglutination)
  – Identifying A-B-O type with known RBCs
    (by agglutination)
              Serology
• Immunoassays
  – EMIT (Enzyme-multiplied immunoassay
    technique)
  – RIA (Radioimmunoassay)
  – Mabs (monoclonal antibodies)
    EMIT




•   An exactly known amount of the enzyme-labeled conjugate (drug, for
    example) is then added to the mixture at which point, binding sites on the
    antibody not occupied by drug molecules become filled with enzyme-labeled
    drug molecules. Only unbound enzyme conjugate is active so that
    conversion of colorless NAD+ to the colored NADH is indicative of the
    amount of free enzyme conjugate and, therefore, drug in the analytical
    sample
       Radioimmunoassay




• Detect amount of
  radioactivity
Mabs
Forensic analysis of
bloodstains
• Blood or not blood
• Species identification
• Association with an individual
    Identifying a stain as blood
• Kastle-Meyer color test
  – Hemoglobin acts like a peroxidase
• Hemastix®
• Luminol test
    Identifying blood as human
• Precipitin test
  – Uses species-
    specific antiserum
  – Excellent
    sensitivity
  – Can be used on
    old blood samples
           Precipitin test
• Gel diffusion
• Gel electrophoresis
  Association of blood with an individual


• Historical methods
  – A-B-O typing
  – Isozyme analysis
     • Polymorphic enzymes
 Association of blood with an individual


• Modern method
  – DNA profiling/typing
 Paternity testing and serology
• Historical method
  – A-B-O typing
  – HLA (Human leukocyte antigen) test
• Modern method
  – DNA profiling/typing
        Serology & semen
• Acid phosphatase color test
• p30 or PSA (prostate specific antigen)
  immunoassays
Serology & semen