Immunosuppressive effects of burn injury and nonspecific blood transfusion.

Burn injuries and blood transfusions both have been implicated as causes of suppressed immune responses. Skin allograft survival in a burned mouse model was studied to determine the relationships among burn injury, blood transfusion, and phlebotomy before transfusion as they affected immunocompetence. At 7 days after 20% TBSA full-thickness burn injury, allograft skin survival was prolonged compared to nonburned control. When increasing volumes of blood were transfused, allograft survival times decreased accordingly. Phlebotomy before transfusion tended to enhance this response. Similar results were seen at 14 days after burn injury, although phlebotomy before transfusion did not further decrease allograft survival time at 14 days. This study demonstrated that blood transfusions were not additively immunosuppressive over burn injury alone. Increased amounts of transfused blood restore allogeneic responsiveness. Phlebotomy may enhance this response when performed early after burn injury.