Professor Reis e Sousa is Principal Scientist in the, Immunobiology Laboratory at Cancer Research UK. He is known for his work on dendritic cell biology. As a graduate student he demonstrated phagocytosis by dendritic cells and followed this with postdoctoral work showing that phagocytosis of particulates can allow presentation of exogenous antigen via the class I pathway. During this period he also showed that dendritic cells act as IL12 producers as well as antigen presenting cells during the initiation of cell-mediated immunity. As an independent investigator his work on dendritic cells has addressed the biology of denedritic cell -T cell interactions; and the mechanisms and signalling pathways involved in pathogen-associated molecular pattern recognition by dendritic cells. His elegant and thoughtful studies have made a major contribution to our understanding of how innate mechanisms interact with and orchestrate the adaptive immune response. Reis e Sousa demonstrated the importance of the nature of initial innate signals in determining which of the mutually opposing cytokines IL12 and IL10 are produced by denedritic cells and the critical role played by T cells in amplification of this initial signal. He has also defined the differences between dendritic cell activation by pathogen-associated molecular pattern recognition and that induced by inflammatory cytokines. In exciting recent work he has found that yeasts can alert dendritic cells to their presence by signalling through a novel syk kinase-dependent pathway.