John W. Semple is a Canadian Scientist formally at St. Michael's Hospital and a Professor of Pharmacology at the

University of Toronto The University of Toronto (UToronto or U of T) is a public university, public research university whose main campus is located on the grounds that surround Queen's Park (Toronto), Queen's Park in Toronto, Ontario, Canada. It was founded by ...

. He is currently a Professor of Transfusion Medicine at Lund University in Sweden. He was born in

Windsor, Ontario Windsor ( ) is a city in southwestern Ontario, Canada. It is situated on the south bank of the Detroit River directly across from the U.S city of Detroit, Detroit, Michigan. Geographically located within but administratively independent of Esse ...

in 1959 and received his PhD in Immunology at Queen's University at

Kingston, Ontario Kingston is a city in Ontario, Canada, on the northeastern end of Lake Ontario. It is at the beginning of the St. Lawrence River and at the mouth of the Cataraqui River, the south end of the Rideau Canal. Kingston is near the Thousand Islands, ...

. In 1991, Semple, along with John Freedman, discovered a

T helper cell The T helper cells (Th cells), also known as CD4+ cells or CD4-positive cells, are a type of T cell that play an important role in the adaptive immune system. They aid the activity of other immune cells by releasing cytokines. They are considere ...

defect in patients with the bleeding disorder called immune thrombocytopenia (ITP). ITP is a condition of having a low platelet count (thrombocytopenia) and most causes appear to be related to antibodies and T cells against platelets. Very low platelet counts can lead to a bleeding diathesis and purpura. The T cell defect was initially shown to be an exaggerated interleukin-2 response when T cells were cultured with platelets in vitro. Subsequently, this cytokine abnormality was shown by others to be responsible for many of the autoimmune mechanisms causing the disorder.). The importance of understanding the T cell defects in ITP is that novel therapies aimed at these cells may significantly benefit patients with ITP.

References

External links

John Semple's laboratory homepage

John Semple's biography at St. Michael's Hospital

1959 births Canadian medical researchers Canadian immunologists Living people Medical educators Queen's University at Kingston alumni People from Windsor, Ontario Scientists from Toronto Academic staff of the University of Toronto 20th-century Canadian scientists 21st-century Canadian scientists {{Canada-med-bio-stub