A series of surveys on assay for anti-A/B antibody by Japanese ABO-incompatible Transplantation Committee

Abstract

Background: The measurement of anti-blood groups A and B antibody (Ab) titers is considered to be important in ABO-incompatible transplantation. However, no standard method for quantitative determination has yet been established in Japan. Inter-examiner variability was likely because Ab titer was determined mainly by visual observation. In order to assess inter-institutional variation in the measurement of anti-A/B Ab titer, a series of surveys was conducted by the Japanese ABO-incompatible Transplantation Committee.

Methods and results: In 2003, the first national survey was conducted. Serum samples from six healthy volunteers with blood groups A (n = 2), B (n = 2) and O (n = 2) were sent to 29 institutions and anti-A/B Ab titer was measured by their customary methods. Isohemagglutinin assay in serial-doubling dilutions of serum using a test tube was widely used in all institutions. Inter-institutional difference between maximum and minimum value reached as much as 32-fold in immunoglobulin M (IgM) and 256-fold in IgG. As detailed protocol for assay seemed to be different between institutions, we attempted to standardize the protocol based on the result of a questionnaire survey. In 2004, a second survey was conducted in the same manner as the previous one, except participation involved 38 institutions and the measurement was performed in a uniform way using a provisional standard protocol. Analysis of the survey revealed that intra-institutional variation was reduced to below eightfold, except that several institutions showed a large difference from the mean titer and required some guidance.

Conclusions: A periodical quality control survey is considered necessary to improve the accuracy of measurement. Anti-A/B Ab titer would provide useful information towards the prediction of rejection and the indication of treatments such as (double filtration) plasmapheresis, splenectomy, anti-CD20 monoclonal antibody and intravenous immunoglobulin. Standardization of the assay for anti-A/B Ab titer is essential for the fulfillment of a precise multicenter study, which will elucidate the significance of the measurement of anti-A/B Ab titer.