John W. Semple

John W. Semple is a Scientist at St. Michael's Hospital and a Professor of Pharmacology at the University of Toronto. He was born in Windsor, Ontario and received his PhD in Immunology at Queen's University at Kingston, Ontario. In 1991, Semple discovered a T helper cell defect (Semple JW et al. Blood. 78(10):2619-2625, 1991) in patients with the bleeding disorder called immune thrombocytopsnic purpura (ITP) where autoantibodies attack platelets and destroy them prematurely. This T cell defect was subsequently shown by other laboratories to be responsible for generating the autoantibodies responsible for low platelet counts in ITP. It has led the way to therapies aimed at reducing the T cell abnormalities in patients with ITP.