General Considerations ITP is an autoimmune disorder in which an lag autoantibody is formed that binds to platelets It is not clear which antigen on the platelet surface is involved. Although the antiplatelet antibody may bind complement, platelets are not destroyed by direct lysis
General Considerations • ITP is an autoimmune disorder in which an IgG autoantibody is formed that binds to platelets • It is not clear which antigen on the platelet surface is involved. • Although the antiplatelet antibody may bind complement, platelets are not destroyed by direct lysis
General Considerations Rather, destruction takes place in the spleen, where splenic macrophages with Fc receptors bind to antibody coated platelets Since the spleen is the major site both of antibody production and platelet sequestration, splenectomy is highly effective therapy
General Considerations • Rather, destruction takes place in the spleen, where splenic macrophages with Fc receptors bind to antibodycoated platelets • Since the spleen is the major site both of antibody production and platelet sequestration, splenectomy is highly effective therapy
General Considerations 1.definition: thrombocyte unrelated to a drug, an infection, or autoimmune disease is generally classified as ITP 2 character: shortened span of platelet increased megakaryocyte in bone marrow 3 classification: acute, chronic
General Considerations 1.definition：thrombocyte unrelated to a drug, an infection, or autoimmune disease is generally classified as ITP 2.character： shortened span of platelet increased megakaryocyte in bone marrow 3.classification：acute, chronic
Mechanism 1.Immunity (1 acute postviral infection immune complex(viral Ag and Ab) connect with platelet Fc-R viral components banding with platelet auto Ab generation (2) chronic: not affected by foreign Ag
Mechanism 1.Immunity （1）acute： postviral infection immune complex (viral Ag and Ab) connect with platelet Fc-R viral components banding with platelet auto Ab generation （2）chronic：not affected by foreign Ag
Mechanism 2. iver and spleen: (1)1/3 platelets are held within the spleen (2) spleen produces platelet associated Ab (3) liver and spleen erase platelet 7-11 days in normal persons, 1-3 days in patients
Mechanism 2.liver and spleen： （1）1/3 platelets are held within the spleen （2）spleen produces platelet associated Ab （3）liver and spleen erase platelet：7-11 days in normal persons, 1-3 days in patients