Granulocyte-Monocyte Apheresis in Steroid-Dependent, Azathioprine-Intolerant/Resistant Moderate Ulcerative Colitis: A Prospective Multicenter Study oleh Gianni Imperiali, Arnaldo Amato, Maria Maddalena Terpin, Ivo Beverina, Aurora Bortoli, Massimo Devani, Chiara Viganò, Study Group on IBD (GSMII)