Anti-B Titre Test – Serum
Overview:
The Anti-B titre test measures the amount of anti-B antibodies in a person's serum. These antibodies target the B antigen found on red blood cells and are naturally present in individuals who lack B antigens—primarily those with blood group A or O. The test is commonly used in blood transfusion medicine, organ transplantation, and maternal-fetal compatibility assessment.

Sample Type:
Serum (blood sample)

Blood is drawn from the patient, and the serum is tested for the presence and strength of anti-B antibodies through agglutination-based serial dilution techniques.

Purpose of the Test:
To evaluate transfusion compatibility, especially in ABO-incompatible cases

To assess risk of hemolytic disease of the newborn (HDN) in pregnancies where the mother and fetus have incompatible ABO blood groups

To determine suitability for ABO-incompatible organ transplantation (e.g., kidney or liver)

To monitor antibody levels after desensitization treatments in transplant candidates

How the Test Works:
The patient’s serum is serially diluted and mixed with type B red blood cells

The highest dilution where visible agglutination (clumping) occurs is recorded as the titre

The titre reflects the strength or concentration of anti-B antibodies present

Interpretation of Results:
High titre: Indicates a strong immune response; increased risk of complications in transfusion or transplantation

Low titre: Lower levels of antibodies; reduced risk of adverse reactions

Used to guide safe transfusion practices and pre-transplant desensitization protocols

Note: Titre values vary by laboratory and clinical context. Clinical judgment is essential when interpreting results.

Clinical Significance:
In transfusions: Ensures ABO compatibility and helps avoid hemolytic transfusion reactions

In pregnancy: High maternal anti-B titres may pose a risk of ABO hemolytic disease in the newborn

In transplants: Helps assess the feasibility of ABO-incompatible transplants and monitor treatment response

Limitations:
Titre levels may fluctuate due to exposure (e.g., prior transfusions, infections, pregnancy)

Results must be interpreted in conjunction with blood group typing, clinical history, and other immunohematological tests

Does not assess antibodies against other blood group systems (e.g., Rh system)
Conclusion:
The Anti-B titre serum test is an essential tool in transfusion medicine, organ transplantation, and obstetrics. It helps quantify anti-B antibody levels, ensuring safe and compatible blood or organ use, and aids in preventing immune-mediated complications in sensitive clinical situations.