Professor Alan Sher received his Ph.D. from the University of California, San Diego, and did his postdoctoral training in the Division of Parasitology at the National Institute for Medical Research in Mill Hill, London. In 1980, after several years as a research associate and then assistant professor in the department of pathology at Harvard Medical School, he joined NIAID as a section chief in the Laboratory of Parasitic Diseases (LPD). Professor Sher became chief of LPD in 2003 and was promoted to NIH Distinguished Investigator in 2011. Professor Sher had major fundamental implications for the areas of host defense and immune regulation. He was pioneer in studying the role of T cells and T-cell cytokines produced in a wide range of parasitic and microbial disease models and played a leading role in creating the modern field of immunoparasitology. Parasites have evolved to co-exist with vertebrate defense mechanisms and Sher's work established the concept that host-parasite interaction can reveal fundamental mechanisms of immune system functioning and control. Professor Sher identified mechanisms by which helminths and extracellular protozoa evade antibody attack and the alternative complementary pathway. Professor Sher, together with Phillip Scott and Robert Coffman, was the first to show that Th1 versus Th2 responses to a parasite (Leishmania) infection determine resistance or susceptibility in mice. He has done seminal work in discovering multiple strategies of parasites to regulate cell-mediated immunity to ensure both parasite and host survival. Professor Sher demonstrated the essential role of dendritic cells and key cytokines, such as IL-12, in starting and regulating the immune responses in parasite infections. In the case of Toxoplasma, he discovered a new toll-like receptor ligand, profilin, which is responsible for activating the function of dendritic cells. Professor Sher published more than 480 publications, mostly in high-ranking journals with more than 70,000 citations. He is one of the most cited immunologists worldwide. In June 2022, Professor Sher closed his laboratory research.