A standardized kodecyte method to quantify ABO antibodies in undiluted plasma of patients before ABO-incompatible kidney transplantation.

BACKGROUND

The ABO transplantation barrier can be breached if antibody is reduced to low levels. Current serologic methods involve testing natural RBCs against dilutions of plasma to determine antibody levels, but these methods are poorly standardized and inherently error prone with consequent large inter- and intra laboratory variation. We evaluated the feasibility of using antigen-standardized kodecytes and undiluted plasma as an alternative method for antibody measurement in patients preparing for ABO-incompatible kidney transplantation.

STUDY DESIGN AND

METHODS

A panel of five kodecytes, bearing defined levels of synthetic blood group A type 2 antigen was developed (kodecyte assay) to show reaction patterns against undiluted plasma that were indicative of anti-A and anti-A,B levels. This panel was evaluated against the contemporary method of testing dilutions of plasma against A1 cells to determine titer (A1 cell assay) in both column agglutination and tube techniques. Evaluation samples included reference standards, 102 group O plus 23 group B donors, and 40 pre- and post-plasmapheresis samples from five prospective ABO-incompatible kidney transplant patients.

RESULTS

Comparisons between the kodecyte and A1 cell assays found greater than 90% correlation for all samples. Tube and column agglutination technology platform differences were observed with A1 cells and kodecytes. Discordant samples were generally found to have high ratios of IgG:IgM or vice versa.

CONCLUSIONS

The kodecyte assay is a simple method that requires no sample dilution, and an optimized two-cell kodecyte panel is potentially capable of informing ABO-incompatible kidney transplantation decisions based on antibody levels.