DEFA3 and autoimmune thrombocytopenic purpura: On the other hand, DEFA3 but not DEFA1, has been found upregulated in patients with systemic lupus erythematosus, idiopathic thrombocytopenic purpura or rheumatoid arthritis, suggesting that DEFA3 upregulation might be a general feature of autoimmune diseases [27,28].