Evaluation of factor VIII deficient plasmas.

Immunodepleted plasmas from Organon Teknika, Dade, Stago, Diagen and the Scottish National Blood Transfusion Service (SNBTS), and haemophilic plasma from Immuno were compared by several laboratories with haemophilic plasma from local donors as substrates in one-stage factor VIII assays. Five clinical plasma samples and four concentrates were assayed against British Standard plasma and International Standard concentrate. Potencies of all plasma samples were not significantly different from those with local haemophilic plasma for Immuno, Organon Teknika, Stago and SNBTS substrates. Dade differed from haemophilic on one sample and Diagen on three. Buffer blank times and slopes of standard lines were similar with all substrates. A positive drift between the beginning and end of the assay was found with the Immuno substrate and a negative drift with the Organon Teknika substrate. In the concentrate study results for all substrate plasmas were not significantly different from haemophilic on the intermediate purity and conventional high purity products. On the monoclonal and recombinant products, there was a tendency for the immunodepleted substrates to give lower potencies than the haemophilic, and significant differences were found with Dade and Stago on the monoclonal concentrate, and with Dade, Stago and Diagen on the recombinant concentrate. Overall, this study indicates that most commercially available substrate plasmas are suitable as replacements for locally collected haemophilic plasma in one-stage assays of clinical samples, and of intermediate purity and conventional high purity concentrates. For assays of very high purity concentrates (monoclonal and recombinant), haemophilic plasma is preferable as some immunodepleted plasmas give low results.