Cryopreservation of hen red blood cells.

The cryoprotection of hen erythrocytes, used as reagent in virus titration, was investigated. The cryoprotective agents tested were neutralized polyvinylpyrrolidone (PVP), dimethylsulfoxide (DMSO) and glycerol. Good results were obtained with PVP, especially with PVP K15 (average molecular weight 10 000), and with DMSO, especially when used in a final concentration of 10 %, whereas glycerol was unfit for use in the concentrations tested. The red cell concentration, the suspending buffer before freezing and the washing procedure after thawing were of importance. The cells could be frozen and stored for at least three months without any significant effect on the virus titer.