Patent ID: 7521174

Claim:
A method of preparing pegylated red blood cells comprising a polyethylene glycol (PEG) having a molecular weight of 5 K daltons and a polyethylene glycol (PEG) having a molecular weight of 20 K daltons, the method comprising the sequential steps of: (a) introducing a polyethylene glycol (PEG) having a molecular weight of 5 K daltons onto the red blood cells to prepare pegylated red blood cells comprising a polyethylene glycol (PEG) having a molecular weight of 5 K daltons, wherein either (1) the red blood cells are contacted with a chemical thiolating compound that produces a thiolated amino group on a membrane protein of the red blood cells and the polyethylene glycol (PEG) is attached to the thiolated amino group via a maleimide or (2) the polyethylene glycol (PEG) is a succinimidyl-propionate-activated (SPA)-polyethylene glycol (PEG); (b) removing excess reagents; and (c) introducing a polyethylene glycol (PEG) having a molecular weight of 20 K daltons onto the pegylated red blood cells comprising the polyethylene glycol (PEG) having a molecular weight of 5 K daltons to prepare pegylated red blood cells comprising a polyethylene glycol (PEG) having a molecular weight of 5 K daltons and a polyethylene glycol (PEG) having a molecular weight of 20 K daltons, wherein either (1) the red blood cells are contacted with a chemical thiolating compound that produces a thiolated amino group on a membrane protein of the red blood cells and the polyethylene glycol (PEG) is attached to the thiolated amino group via a maleimide or (2) the polyethylene glycol (PEG) is a succinimidyl-propionate-activated (SPA)-polyethylene glycol (PEG); wherein the polyethylene glycol (PEG) is a methoxy PEG; and wherein pegylation of the red blood cells masks a Rh antigen and one or more of A antigen and B antigen.