PD-1 Is Elevated on the Peripheral Blood T Cell Subsets of Patients with Relapsed/Refractory Hodgkin Lymphoma Compared to Normal Volunteers - Diefenbach, Catherine S.; Sabado, Rachel; Clark-Garvey, Sean; Cruz, Crystal; Vengco, Isabelita; Rojas, Celeste N; Serrano, Victoria; Zain, Jasmine M.; Cho, Hearn J.; O'Connor, Owen A. (Blood, 2011)