Marina Botto is Professor of Rheumatology at Imperial College London. She has made extensive contributions to our understanding of complement regulation and of Systemic Lupus Erythematosus. In the early 1990s she established the gene structure of complement factor C3 in humans. Her subsequent mechanistic studies in mice have shown the importance of complement in clearing dying cells and immune complexes, with consequent development of autoimmunity when regulation of the complement system fails. Recently, her laboratory has developed a mouse model of haemolytic uraemic syndrome and used this to establish that the complement factor C5 plays a critical role in renal injury, leading to the proposed use of anti-C5 antibodies in renal and other inflammatory diseases.