Lymphokine Testing Laboratory (LTL) - The Lymphokine Testing Laboratory (LTL) maintains the on-site cytokine repository for the Biological Resources Branch (BRB), NCI. This repository provides cancer research support by providing antibodies and cytokine reagents to approved investigators for use in basic research. In FY2008 there were 17 requests for BRB repository products from investigators at NCI-Frederick and one request for materials to be sent to an investigator at another institution. The laboratory staff maintains an inventory of products supplied by BRB. Upon request, the laboratory performs bioassays to evaluate that BRB repository products have maintained activity and are suitable for use as research reagents. When requested, the laboratory provides support to drug development by working with BRB investigators and the Biopharmaceutical Development Program staff to develop or transfer bioassays that can be used for assessing product bioactivity. In FY2008 this included participation in meetings related to IL-15 and the Miltenyi anti-CD45RA product.The Lymphokine Testing Laboratory provides support to clinical trials through recertification testing of the biological activity of cytokines being used in NCI-sponsored clinical trials. Recertification testing requires the laboratory to precisely duplicate the test conditions used by the original product supplier and to match test results used to establish the bioactivity of the cytokine product. Once the assays have been translated to the laboratory, the assays are validated against international standards, when available, prior to initiating product testing. In some cases it is necessary for the laboratory to modify or develop the assays to be used for testing and to provide documentation that the assay is validated and provides reproducible results. Each of the assays currently in use by the laboratory requires maintenance of cell lines required to demonstrate biological activity of the test material. During FY2008, LTL performed recertification testing of biological activity of clinical grade interleukin-4 using a TF-1 cell line proliferation assay. LTL performed two sets of recertification testing of the biological activity of clinical grade interleukin-6 using a T1165 murine plasmacytoma proliferation assay. These assays showed that the IL-6 maintained biological activity. LTL performed bioassays to recertify the biological activity of Interleukin-12 (IL-12) from Wyeth Research. The assay is a 3H-thymidine incorporation assay using proliferation of the KIT225K6 cell line and involves co-stimulation of cells with a fixed dose of IL-4 and dilutions of IL-12.