Test Details: Antibodies may be produced when your immune system mistakenly considers healthy tissue to be a harmful substance. In the case of platelet antibodies, body creates antibodies to attack platelets. As a result, there is a lower than normal number of platelets in the body. Anti-platelet antibodies may be due to unknown reasons ( Idiopathic Thrombocytoenic Purpura ), due to side effect of drugs such as quinine, heparin, quinidine among other causes.