EVALUATION OF FACTOR-VIII DEFICIENT PLASMAS

Immunodepleted plasmas from Organon Teknika, Dade, Stago, Diagen and t he Scottish National Blood Transfusion Service (SNBTS), and haemophili c plasma from Immuno were compared by several laboratories with haemop hilic plasma from local donors as substrates in one-stage factor VIII assays. Five clinical plasma samples and four concentrates were assaye d against British Standard plasma and International Standard concentra te. Potencies of all plasma samples were not significantly different f rom those with local haemophilic plasma for Immuno, Organon Teknika, S tago and SNBTS substrates. Dade differed from haemophilic on one sampl e and Diagen on three. Buffer blank times and slopes of standard lines were similar with all substrates. A positive drift between the beginn ing and end of the assay was found with the Immuno substrate and a neg ative drift with the Organon Teknika substrate. In the concentrate stu dy results for all substrate plasmas were not significantly different from haemophilic on the intermediate purity and conventional high puri ty products. On the monoclonal and recombinant products, there was a t endency 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 mos t commercially available substrate plasmas are suitable as replacement s for locally collected haemophilic plasma in one-stage assays of clin ical 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 immunodeple ted plasmas give low results.