CXCL13 and thrombotic thrombocytopenic purpura: CXCL13 levels among ESRD secondary to clinical autoimmunity (four type I diabetes and one TTP) (n = 5; 90 pg/ml; 70–800 pg/ml) did not differ from ESRD patients without clinical autoimmunity, P = 0.85 (data not shown).