EAC Rosette-Forming Lymphocytes in Commercial Preparations of Sheep Erythrocytes

In vitro enumeration of human complement (C3) receptor-bearing lymphocytes is routinely performed with sheep erythrocytes (E) sensitized with 19S anti-sheep erythrocyte antibody (A) and fresh mouse complement (C), termed the EAC reagent (1). Sheep whole blood diluted with an equal volume of Alsever's solution is washed with saline and used to prepare the EAC reagent. It is assumed that the residual sheep leukocytes in the solution are rapidly lost upon storage after the blood is collected. However, here we report finding considerable numbers of residual sheep lymphocytes in sheep blood in Alsever's solution up to 30 days after storage at 4°C. In addition, one finds that about 75% of these residual sheep lymphocytes form autorosettes with the EAC reagent. Preparations of whole sheep blood diluted with an equal volume of Alsever's solution were obtained from a commercial source, and samples were assessed for the presence and viability of lymphocytes starting with the day the blood was drawn and continuing for 4 weeks.