Lot release testing of serological infectious disease assays used for donor and donation screening

Monitoring of the ongoing performance of infectious disease screening assays is a critical part of any donation screening programme. Although assay sensitivity is formally evaluated prior to implementation, it is essential that this level of performance is maintained from lot-to-lot. In 2002, National Health Service Blood and Transplant developed and implemented a formal system for the lot release testing of serology infectious disease screening assays.

Lot release panels were prepared for each of the serological screening markers. They each comprise 10-15 members and include both genuine low-titre and diluted high-titre materials. For each panel member, a minimum reactivity is expected, based upon the formal sensitivity evaluation of each assay. All new lots of the screening assays used are assessed prior to supply of the lot to the organization.

Since 2002, a total of 887 different lots of the serology screening assays used have been supplied. Of these, 876 (98.8%) passed lot release and were authorized for supply to the organization. Eleven lots (1.2%) were failed because the lots did not meet the release criteria or were unsuitable for some other reason.

The lot release system has proved to be effective in objectively assessing assay performance to ensure that there is no significant lot-to-lot variation such that the performance of the assay may fall below that originally determined at evaluation. The few assays that have failed lot release did have proven performance issues that were subsequently accepted by the manufacturers. CONTENTS SUMMARY: Description of the Lot Release Testing system for serology infectious disease screening assays in use within NHSBT with a critical analysis and review of the data generated in the 7 years that the system has been in use.