Warren J. Leonard is an immunologist and world leader in the area of cytokines. He is particularly known for cloning the IL-2 receptor alpha chain, co-discovering IL-2RBeta, and demonstrating that the IL-2 receptor y chain is mutated in human Xlinked severe-combined immunodeficiency (XSCID) and is a shared receptor component by multiple cytokines. He also discovered JAK3- and IL7R-deficient SCID, cloned IL-21R, and elucidated the biology, signaling, induced expression patterns, and molecular regulation of y c-family cytokines, with discoveries leading to novel diagnostics and therapeutics. Leonard was born in Washington, DC in 1952 and grew up in Bethesda. He graduated with an A.B. in mathematics magna cum laude from Princeton University in 1973 and an M.D. from Stanford University in 1977, followed by a residency in internal medicine. He was a postdoctoral fellow in the National Cancer Institute and started his own lab at NIH in 1985. He is past-president of the International Cytokine Society, was co-Editor of Immunity, is a member of the Council of the Association of American Physicians, recipient of the AAI-Huang Foundation Meritorious Career Award and the International Cytokine and Interferon Society Honorary Lifetime Membership Award, and a member of the National Academy of Sciences and the National Academy of Medicine.

Research Interests

Warren J. Leonard's laboratory is interested in the regulation of the immune response, with particular focus on the actions of hormones of the immune system known as cytokines. Using primary cells from normal donors and patients as well as genetically altered transgenic, knockout, and knockin mice, the laboratory has elucidated the biological importance of yc family cytokines (IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21) and a closely related cytokine, thymic stromal lymphopoietin (TSLP) both in normal physiology and pathogenic states, including immunodeficiency and in response to viral infection or in models of allergic inflammation, autoimmune disease, and inflammatory bowel disease. Specifically, the lab has elucidated key actions of IL-2 in promoting T helper cell differentiation, the role of IL-21 in autoimmune disease and B cell differentiation, the role of TSLP in allergic inflammation, and made broad mechanistic insights into the actions of these cytokines, particularly via STAT proteins, including in their global regulation of gene expression based in part of the use of genomewide next generation sequencing. Work from the lab also contributed to the scientific foundation for the development of JAK inhibitors and the first study of partial agonists for a cytokine.

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Primary Section

Section 43: Immunology and Inflammation

Secondary Section

Section 41: Medical Genetics, Hematology, and Oncology