1. Antibodies produced by an individual against antigens from another individual of the same species, typically arising from transfusion, pregnancy, or transplantation.
Usage: medical/immunology term; plural form; singular is alloantibody; also called isoantibodies in older literature

Examples

• Patients who receive multiple blood transfusions may develop alloantibodies against donor red blood cells.
• Alloantibodies can complicate pregnancy if a mother's immune system reacts against fetal antigens.
• The laboratory tested the patient's serum for alloantibodies before scheduling the organ transplant.
• Hemolytic transfusion reactions can occur when alloantibodies in the recipient's blood attack transfused cells.
• Alloimmunization from previous transfusions led to the formation of dangerous alloantibodies.