EFFECT OF PRESENSITIZATION ON MIXED LYMPHOCYTE REACTION OF RAT SPLEEN CELL CULTURES

The patterns of deoxyribonucleic acid synthesis and cell survival were studied in mixed spleen cell cultures from normal and crossimmunized inbred rats. In mixed cultures from nonsensitized animals, the peak of tritiated thymidine (3H-TdR) incorporation took place at the 7th day in culture, and there was a steady decrease of cell survival throughout the culture period. In mixed cultures from rats sensitized 4 days previously with spleen and lymph node cells of the opposite strain, the patterns were markedly different: there was an early high peak of 3H-TdR incorporation followed by a rapid decline to values lower than those observed in nonmixed control cultures. At the time of decline of 3H-TdR incorporation in mixed presensitized cultures, there was an abrupt decline of cell viability. The sera from the sensitized animals was not cytotoxic in the system, and the cultures from the sensitized rats responded to phytohemagglutinin stimulation as well as those from nonsensitized rats. It is proposed that both afferent and efferent arms of the cellular immune response develop in cultures of allogeneic lymphoid cells. © 1969 by The Williams and Wilkins Co.