Summary
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.
