John W. Semple Explained

John W. Semple is a Canadian Scientist formally at St. Michael's Hospital and a Professor of Pharmacology at the University of Toronto. He is currently a Professor of Transfusion Medicine at Lund University in Sweden. He was born in Windsor, Ontario in 1959 and received his PhD in Immunology at Queen's University at Kingston, Ontario. In 1991, Semple, along with John Freedman, discovered a T helper cell defect in patients with the bleeding disorder called immune thrombocytopenia (ITP).^[1] 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.).^{[2] [3] [4] [5] [6]} The importance of understanding the T cell defects in ITP is that novel therapies aimed at these cells may significantly benefit patients with ITP.

External links

• John Semple's laboratory homepage
• John Semple's biography at St. Michael's Hospital
• John Semple's biography at the University of Toronto

Notes and References

1. JW. Semple. Increased antiplatelet T helper lymphocyte reactivity in patients with autoimmune thrombocytopenia . . 78 . 2619–25 . 1991 . 1840468 . 10 . etal . 10.1182/blood.V78.10.2619.2619. free .
2. N Cooper. The pathogenesis of immune thrombocytopaenic purpura . . 133 . 364–374 . 2006 . 16643442 . 4 . 10.1111/j.1365-2141.2006.06024.x . 18116618 . etal.
3. JW Semple. Differences in serum cytokine levels in acute and chronic autoimmune thrombocytopenic purpura: relationship to platelet phenotype and antiplatelet T-cell reactivity . . 87 . 4245–4254 . 1996 . 8639783 . 10 . etal . 10.1182/blood.v87.10.4245.bloodjournal87104245. free .
4. M Kuwana. Autoreactive T cells to platelet GPIIb-IIIa in immune thrombocytopenic purpura. Role in production of anti-platelet autoantibody . . 102 . 1393–1402 . 1998 . 9769332 . 7 . 10.1172/JCI4238 . 508987 . etal.
5. B Olsson. T-cell-mediated cytotoxicity toward platelets in chronic idiopathic thrombocytopenic purpura . . 9 . 1123–1124 . 2003 . 12937414 . 9 . 10.1038/nm921 . 1255875 . etal.
6. Stasi R, etal . Analysis of regulatory T cell changes in patients with idiopathic thrombocytopenic purpura receiving B-cell depleting therapy with rituximab . . 112 . 1147–1150 . 2008 . 18375792 . 4 . 10.1182/blood-2007-12-129262 . free .