The use of frozen erythrocytes in the single radial haemolysis test (SRHT) for antibodies to rubella virus.

The cryoprotection of erythrocytes from newborn chickens was investigated. The cryoprotective agents tested were neutralized polyvinylpyrrolidone (PVP), dimethylsulfoxide (DMSO) and glycerol. Best results were obtained with 10 per cent DMSO, whereas 20 per cent DMSO and glycerol were unfit for use. The red cell concentration and the temperature of freezing and thawing were of importance. Recovery of cells after thawing was most successful when the cells had been frozen at a concentration of 5 per cent, and best results were obtained when the cells were frozen directly in liquid nitrogen (-196 degrees C). Frozen and thawed chicken cells were used in the single radial haemolysis test (SRHT) for the assay of rubella antibody, and compared with frozen and thawed erythrocytes from hen and sheep. Haemagglutinin (HA) absorbed sheep erythrocytes could be frozen in small quantities and used directly in the SRHT plates whereas frozen erythrocytes from newborn chickens and hen had to be washed before use in the SRHT phase.