alloimmunized

adjective

al·​lo·​im·​mu·​nized ˌa-lō-ˈi-myə-ˌnīzd 

: having undergone isoimmunization

Alloimmunized patients can be extremely difficult to treat with platelet transfusions; the likelihood of finding HLA-matched donors is often limited, and maneuvers to blunt the antibody response or interfere with immune destruction have been unsuccessful.

—Margot S. Kruskall, The New England Journal of Medicine