Collaborative study to recalibrate the International Reference Preparation of Anti-D Immunoglobulin

A collaborative study involving nine independent assays by eight laboratories has recalibrated the anti-D concentration of the International Reference Preparation of Anti-D Immunoglobulin (68/417) in terms of the International Standard for Anti-Rho (anti-D) Incomplete Blood Typing Serum (64/16). This study was carried out when it was found that 68/419 had been calibrated not against 64/16, as originally intended, but inadvertently against another preparation. Based on the results, a revised rounded off value of 300 IU anti-D per ampoule of 68/419 was assigned by the Expert Committee on Biological Standardisation of WHO at its 30th meeting. Many of the known variables in anti-D quantitation using the AutoAnalyzer were considered in the preparation of the protocol for this study. The remarkably close agreement of the results indicated that the format can be used as an acceptable model for interlaboratory studies in the future.