Effect of the In Vitro Ageing on the Restriction of Sheep Erythrocyte Lysis by Horse Serum

Fresh sheep erythrocytes are resistant to lysis by horse serum but gradually became susceptible to this source of complement after storage (ageing) in the blood at 4°C, This occurs faster when the fresh cells are stored in isotonic buffer. The supernatant of the buffer/red cell suspension stored at 4°C for 10–15 days restrict lysis by horse serum when incubated back at 37°C or 43°C with the ‘aged’ sheep cells or fresh guinea pig red cells. In assays using fresh guinea pig erythrocytes this effect is decreased by reincubation of the cells in buffer, and is specific to horse serum when compared to human serum.