Cryoprotective effect of gelatin and albumin on recombinant human tumor necrosis factor liposome.

A search for a cryoprotective agent of a liposome containing recombinant human tumor necrosis factor (rHuTNF) was undertaken. Various additives were added and liposomes were freeze-thawed. As a result of these studies, albumin and gelatin were found to suppress the leakage of rHuTNF from liposome. This cryoprotective effect was only observed when the additives were added to the inside of the liposomal membrane; their addition to the outside of the membrane stimulated the leakage. This characteristic was clearly different from well-known cryoprotective agents, such as saccharides which have the cryoprotective effect on both sides of the liposomal membrane. Although this cryoprotective effect was also observed for recombinant human interleukin-1 alpha (rHuIL-1 alpha), it was not observed for fluorescein sodium. These effects of gelatin and albumin were restricted to macromolecular proteins such as rHuTNF and rHuIL-1 alpha, but both substances were very effective cryoprotectants for a liposome containing protein.