Comparison of antibody titers using conventional tube technique versus column agglutination technique in ABO blood group incompatible renal transplant

INTRODUCTION Measurement of alloantibody titer to a red cell antigen (ABO titers) is an integral part of management of ABO incompatible kidney transplants (ABOiKT). MATERIAL AND METHODS There are different methods of titer estimation. Alloantibody detection by tube titration and Gel agglutination columns are accepted methodologies. It is essential to find the difference in titers between the two methods so as to set the 'cut-off' titer accordingly, depending upon the method used. RESULTS We did a prospective observational study to compare and correlate the ABO titers using these two different techniques - conventional tube technique (CTT) and the newer column agglutination technique (CAT). A total of 67 samples were processed in parallel for anti-A/B antibodies by both tube dilution and column agglutination methods. The mean titer by conventional tube method was 38.5 + 96.6 and by the column agglutination test was 96.4 + 225. The samples correlated well with Spearman rho correlation coefficient of 0.94 (P = 0.01). CONCLUSION The column agglutination method for anti A/B titer estimation in an ABO incompatible kidney transplant is more sensitive, with the column agglutination results being approximately two and half fold higher (one more dilution) than that of tube method.