The International Standard for anti-Rh (anti-D) Incomplete Blood-Typing Serum

Area of Science:

• Immunology
• Hematology
• Biotechnology

Background:

• The World Health Organization (WHO) Expert Committee on Biological Standardization initiated efforts to standardize anti-Rh(o) (anti-D) blood-typing serum.
• Accurate RhD typing is critical for preventing hemolytic disease of the newborn.

Purpose of the Study:

• To establish an international standard for albumin-potentiated anti-Rh(o) (anti-D) blood-typing serum.
• To define an International Unit for this standard to ensure global consistency in RhD antibody testing.

Main Methods:

• Collection, testing, and purification of human sera containing anti-Rh(o) (anti-D) antibodies.
• Pooling of selected sera, freeze-drying, and distribution of 3350 ampoules to international laboratories.
• Collaborative testing by 29 laboratories in 21 countries using four different serological methods (albumin suspension, albumin replacement, enzyme, and anti-human-globulin tests).

Main Results:

• The collaborative study demonstrated high consistency in antibody titres across different methods and laboratories.
• The freeze-dried serum material was successfully established as the International Standard for Anti-Rh(o) (Anti-D) Incomplete Blood-Typing Serum.
• An International Unit was defined, equivalent to the activity in 0.95 mg of the established standard.

Conclusions:

• The established international standard provides a reliable reference for anti-Rh(o) (anti-D) blood-typing serum.
• The defined International Unit facilitates accurate and reproducible RhD antibody quantification globally.
• Standardization improves the quality and comparability of blood grouping tests worldwide.