Antibodies to CD44 as a potential replacement for IVIg in ITP

Intravenous immunoglobulin (IVIg) is a therapeutic product which is manufactured by Canadian blood services from plasma donated by healthy blood donors. Canada only collects enough plasma to make 30% of the IVIg that is needed for Canadian patients (the rest comes from the USA). One disease that benefits from IVIg is an autoimmune disease called immune thrombocytopenic purpura (ITP). ITP patients have low platelet numbers in their blood. Because platelets are impmiant in controlling bleeding, many of these patients bleed for a long period of time when they have an injury or can have critical problems when they need surgery or have a tooth extracted. Many patients with ITP have purple marks on their skin because oftheir bleeding. A small percentage of patients (both children and adults) actually die from ITP. We are trying to make a safe substitute for IVIg in our laboratory and have succeeded in making one that can be used to treat mice with laboratory induced ITP. The exact mechanism of these antibodies is not precisely understood (like IVIg) and this grant attempts to understand how these antibodies make the mice better (increase their platelet numbers in blood). The antibodies which we have developed are called "CD44 antibodies". We hypothesize that these CD44 antibodies bind to cells in the immune system that are involved in destroying platelets in ITP and decreasing the activity of these cells so that they do not destroy platelets. When this grant is finished we will know more about how CD44 antibodies make mice with ITP better and we will then try to make an antibody that can be used to treat human patients with ITP and other diseases.
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St. Michael's Hospital
Intramural Research Grant Program
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