Abstract: Disclosed is an improved process for irradiating cell-containing compositions, especially, red cell-containing compositions, wherein vitamin E or a derivative thereof is added to the cell-containing composition prior to, during or after such irradiation. Addition of vitamin E or a derivative thereof is protective of cells in such compositions, but not of virus. Cells irradiated using the inventive process show a reduced leakage of K+ from cells and also a reduced loss of negative charges from the cell membrane compared to cells subjected to the similar process wherein vitamin E or a derivative thereof are not used. In addition, red blood cells sterilized by this process are better preserved during storage and their life-time in the circulation in vivo is greatly enhanced.

Abstract: An improved process is disclosed for photodynamically inactivating viruses in red blood cell containing compositions by adding vitamin E or a derivative thereof, such as Trolox, to the red blood cell and photosensitizer containing composition prior to irradiation. Addition of vitamin E or derivative thereof is protective of the red blood cells but not the viruses to be inactivated. Cells irradiated in this manner exhibit reduced leakage of potassium ion, and reduced loss of negative charges from the cell membrane compared to cells treated in the absence of vitamin E or derivative. Red blood cells sterilized by this method are better preserved during storage and their life-time in the circulation in vivo is enhanced.

Abstract: A red blood cell containing composition is presented which has reduced potassium ion leakage after irradiation in a virus photoinactivation process. The irradiated red blood cell containing composition comprises red blood cells, a photosensitizer, and sufficient vitamin E or derivatives thereof to prevent potassium leakage. Preferred photosensitizers are aluminum phthalocyanines, AlPcS.sub.4 or Pc5. A preferred vitamin E derivative is Trolox.