Antenatal monitoring of anti-D and anti-c: could titre scores determined by column agglutination technology replace continuous flow analyser quantification?

OBJECTIVE

To determine if column agglutination technology (CAT) for titration of anti-D and anti-c concentrations produces comparable results to those obtained by continuous flow analyser (CFA).

BACKGROUND

Anti-D and anti-c are the two commonest antibodies that contribute to serious haemolytic disease of the foetus and neonate (HDFN). Current practice in the UK is to monitor these antibodies by CFA quantification, which is considered more reproducible and less subjective than manual titration by tube IAT (indirect antiglobulin test). CAT is widely used in transfusion laboratory practice and provides a more objective endpoint than tube technique.

MATERIALS AND METHODS

Antenatal samples were (i) quantified using CFA and (ii) titrated using CAT with the reaction strength recorded by a card reader and expressed as a titre score (TS).

RESULTS

The TS rose in accordance with levels measured by quantification and was able to distinguish antibody levels above and below the threshold of clinical significance.

CONCLUSION

CAT titre scores provided a simple and reproducible method to monitor anti-D and anti-c levels. The method was sensitive to a wide range of antibody levels as determined by quantification. This technique may have the potential to replace CFA quantification by identifying those cases that require closer monitoring for potential HDFN.