Importance of Lab Tests for the Presence of Antibodies:

• Assess patient health status
• Document antibody levels
  1. Indicates past infection (e.g., HIV)
  2. Higher antibody levels suggest better recovery chances

Titer Definition: 

Level of specific serum immunoglobulins (antibodies in blood)

Indirect Coombs Test:

• Detects blood incompatibilities
  • Example: Hemolytic Disease of the Newborn (Rh incompatibility)
  • Prior to blood transfusions
• Procedure:

1. 1. Collect recipient’s serum (antibodies)
   2. Mix recipient’s antibodies with donor’s blood sample
   3. Check for agglutination (indicates incompatibility)
   4. Use anti-human antibodies for further confirmation of agglutination

ELISA (Enzyme-Linked Immunosorbent Assay):

• Detects antibody levels in blood
  • Example: HIV or rubella exposure
• Procedure:

1. 1. Plate with virus antigens (e.g., HIV) at the bottom
   2. Add patient’s blood to the plate
   3. Add synthetic anti-HIV antibodies with color/light marker
   4. Observe binding and colour change
      • No colour change indicates presence of patient’s anti-HIV antibodies
   5. Confirm with a Western blot (detects actual HIV or rubella antigens)

Summary:

• Lab tests like Indirect Coombs and ELISA are crucial for assessing blood compatibility and detecting infections.
• Indirect Coombs test is used for blood compatibility (e.g., Rh factor).
• ELISA is used to detect specific antibodies indicating infection.
• Confirmatory tests, like the Western blot, validate initial findings.
• DNA tests can also be used to detect and identify the presence of some infections.