Program ARCT is for donor centers and transfusion laboratories performing automated red cell phenotyping for the management of patients with complex serology (ie, alloimmunization, sickle cell disease, warm autoimmune hemolytic anemia). Challenges will include antigens such as Rh, Kell, Duffy, and Kidd blood group system. Due to the use of donor-based materials, enrollment in this program may be limited.