One of the major challenges for consistently measuring the performance of affinity chromatography resins like Eshmuno® P is the availability of a standard model molecule in its purest form. This is based on the fact that the anti-A or anti-B immunoglobulins are only present in trace levels in pooled plasma, and purification of these is typically not the focus of the process. Normally, the levels of anti-A and anti-B immunoglobulins are determined and characterized by agglutination assays. The same assays can be used to characterize the performance of Eshmuno® P resins in terms of reduction in titers. However, these assays are highly variable and rely on pools with varying titers. Consequently, performance of Eshmuno® P resins, measured in terms of reduction in isoagglutinin levels, could be impacted by the pool titers, and is therefore, subject to variabilities in the agglutination assay.
To reduce the variability in the measurement of the anti-A and anti-B titers, an assay was developed for the routine quality control testing of Eshmuno® P resins. The assay is highly simplified, and involves measuring the depletion of the anti-A or anti-B forms of IgM after incubation with respective Eshmuno® P resin using UV spectroscopy. The monoclonal anti-A or anti-B IgM are obtained in their purest form and at a known concentration by purification of cell culture.