Dr. Shilyansky studies the immune response in pediatric cancer patients. Specifically the mechanism allowing cancers to avoid immune destruction are being addressed. By understanding these mechanisms vaccines that can induce anti-cancer immunity and lead to cancer regression may be developed. Dendritic cells, white blood cells that regulate the immune response, are critically important for effective anti-tumor responses. Cancer cells appear adept at inhibiting dendritic cells. Recent studies in the laboratory examined phosphatidylserine as a mechanism for inhibiting dendritic cells and for evading tumor immunity. Phosphatidylserine is a membrane phospholipid that is normally restricted to the inner surface of the cell membrane (envelope) and is exposed on the cell surface during programmed cell death (apoptosis). However, live cancer cells can express phosphatidylserine on the cell surface. Dr. Shilyansky's laboratory has demonstrated that tumor phosphatidylserine inhibits human peripheral blood derived dendritic cells. Phosphatidylserine appear to interfere with NF-kappaB and p38 MAPK activation, signaling events required for dendritic cell maturation and function. Recent work has concentrated on the in vivo mechanisms by which phosphatidylserine affects tumor immunity. Additional studies in Dr. Shilyansky's laboratory relate to cancer vaccine development and effects of ligating CD40, a critical receptor on antigen presenting cells, in tumor immunity.