Method for sterilizing lyophilized eukaryotic anuclear cells with gamma irradiation

The invention provides a method for the sterilization of a biological preparation comprising desired viable biological entities. The method comprises irradiating a dried (e.g. freeze-dried) biological preparation with ionizing or UV radiation at an intensity and for a duration sufficient to reduce the amount or activity of living-matter contaminants in the biological preparation, the intensity and duration selected such that at least part of the desired biological entities in the sample remains viable. The method of the invention is particularly suitable for the reduction of the amount or activity of contaminants such as bacteria or viruses from biological preparations comprising red blood cells or platelets.