Royal Swedish Academy of Sciences — Crafoord Prize Lectures

Fred Ramsdell traces the discovery of FOXP3 from the striking immune phenotype of the scurfy mouse to the mapping and cloning of the responsible gene. He explains how linking a disease phenotype to its genetic cause opened a route to understanding the regulation of immune responses and the biology of regulatory T cells. The lecture considers FOXP3 as a regulator of immune function and the implications of this history for therapeutic intervention. It argues for the continuing value of phenotype-first research and naturally occurring disease mutations in discovering biological mechanisms and identifying potential treatment targets, even as genome sequencing becomes increasingly routine.

Alexander Rudensky examines why an immune system capable of amplifying responses to pathogens also needs a dedicated mechanism of restraint. He connects the activity of effector CD4 T cells to the emergence of regulatory T cells and explores how loss of this regulatory population accounts for the severe disease associated with FOXP3 deficiency. The lecture follows genetic experiments that test the continuing requirement for regulatory T cells and trace the stability of their lineage. It also considers regulatory T cells generated outside the thymus, their relationship with commensal microorganisms, and their role in limiting inflammation at mucosal barriers. Together these studies explain how a specialised cell lineage can maintain immune tolerance throughout life.

Shimon Sakaguchi explains how regulatory T cells restrain immune responses and maintain tolerance to the body’s own tissues. He follows experimental evidence linking the removal of particular CD4 T-cell populations to autoimmune disease and the restoration of regulation to protection against excessive immune activity. The lecture connects these mouse experiments with human immune dysregulation, including IPEX, and with the role of FOXP3 in regulatory T-cell biology. It develops the idea that active cellular suppression is a continuing requirement for immune balance, with implications for understanding autoimmunity and for manipulating immune responses therapeutically.