Freezing of rat lymphocytes. III. Freezing of plaque-forming cells and restoration by frozen-thawed normal cells of antibody production in irradiated rats.

The present investigation is an extension of earlier work with dimethyl sulphoxide (DMSO) protected frozen-thawed rat lymphocytes. In the present work it is shown that some 85-90% of the haemolytic plaque-forming cells (PFC) survived the freeze-thaw process. Irradiated rats were restored with fresh and frozen-thawed cells and immunized against sheep red blood cells (SRBC). Evidence is presented that a restrictive control of the PFC response by suppressor cells present in the spleen cell suspension is lost during the freeze-thaw process, giving a higher number of PFC/spleen in recipients of frozen-thawed mixed spleen and lymph node cells than in rats receiving the corresponding fresh preparations.