International collaborative study to establish reference preparations to standardise haemagglutination testing for Anti-A and Anti-B in normal intravenous Immunoglobulins by the direct method

A joint project (coded BSP089) was run by the European Directorate for the Quality of Medicines & HealthCare (EDQM)of the Council of Europe, the National Institute for Biological Standards and Control (NIBSC) on behalf of the WorldHealth Organization (WHO) and the Center for Biologics Evaluation and Research (CBER) of the U.S. Food and DrugAdministration (FDA) to evaluate, in an international collaborative study, 3 lyophilised intravenous immunoglobulin(IVIG) preparations for their suitability to serve as Reference Preparations to standardise and control the highly variablehaemagglutination testing for anti-A and anti-B in IVIG products.23 laboratories tested candidate IVIG reference preparations consisting of a Positive control, a Negative control anda specifically formulated Limit test reference preparation to define the maximum (e.g., pharmacopoeial) limits ofanti-A and anti-B haemagglutinins in IVIG products, where limits are applicable. Laboratories performed directhaemagglutination using papain-treated erythrocytes and/or indirect anti-globulin tests.For both methods, there was up to 16-fold variation in anti-A and anti-B titres, although there was good agreement over a2-fold titre range for anti-A and anti-B between laboratories using the direct method for both the Positive control andLimit reference preparations. Comparative titration data for the Positive control and Limit reference preparationsindicated that the use of a 'Limit' test reference preparation would facilitate identification of higher titre batches whenthe direct haemagglutination method is used.The Positive control, Negative control and Limit test preparations were adopted in November 2008 by the Commissionof the European Pharmacopoeia (Ph. Eur.) as Biological Reference Preparations. The same preparations have beenestablished as reference reagents by the WHO and the U.S FDA, including the maximal specifications defined by theLimit test preparation. This will facilitate global standardisation of haemagglutination tests for anti-A and anti-B, ensurethat such tests are sufficiently sensitive and specific, and facilitate identification of batches that exceed maximumrecommended levels of anti-A and anti-B antibodies.