Which of these blood products needs to be irradiated before being transfused into a patient?

Granulocytes require irradiation before transfusion to a patient primarily to prevent transfusion-associated graft-versus-host disease (TA-GVHD). This condition can occur when transfused immune cells attack the recipient's tissues. Granulocytes, being rich in leukocytes, pose a higher risk for this complication.

Irradiation inactivates lymphocytes present in the blood product, significantly reducing the risk of TA-GVHD. This is especially crucial for patients who are immunocompromised, such as those with certain cancers or undergoing stem cell transplants, as they are more susceptible to such reactions.

While erythrocytes, fresh frozen plasma, and platelets are important blood products, they do not routinely require irradiation unless specific circumstances are present, such as a history of TA-GVHD in the recipient or certain types of immunosuppression. Erythrocytes are typically used for anemia, fresh frozen plasma for coagulopathies, and platelets for thrombocytopenia, but none carry the same risk of TA-GVHD as granulocytes.