Significant focus is being placed on the utility of in vitro models to assess immunomodulation. In vitro cytokine release assays were used to evaluate the ability of 18 perfluoroalkyl substances to modulate cell proliferation and cytokine secretion in human peripheral blood lymphocytes. In vitro cytokine release assays were also used to screen for biological activity in several batches of echinacea purpurea. Results from the in vitro screen and endotoxin assessments were used to select a test article for in vivo studies. We have partnered with the Interagency Coordination Committee on the Validation of Alternative methods and are using recently published combinations of non-proprietary in vitro assays to evaluate the potential for a variety of chemicals to induce skin sensitization. Nominations were received from multiple ICCVAM agency partners and industry collaborators. Approximately 200 compounds are being screened in multiple assays. Draft reports for studies on formulations received through an industry collaboration and Isothiozolinone compounds nominated by the Environmental Protection agency have been received, reviewed and are undergoing finalization.