The interaction of normal lymphocytes and cells from lymphoid cell lines. I. The nature of the activation process

Human peripheral lymphocytes from all donors tested were mitotically activated when cultured in the presence of X-irradiated cells from continuously cultivated lymphoid cell lines (LCL). X-irradiated cells from LCL originating from normal individuals were effective as well as those of Burkitt's tumour origin and cells from LCL reported to be free of herpes-like virus were as effective as those reported to contain virus. The activation was of much greater intensity than the normal mixed lymphocyte reaction but occurred over a similar culture period. The reaction occurred only under conditions permitting direct cell contact between the two populations of cells. Most stimulation was obtained with viable X-irradiated LCL cells. Disrupted LCL cells were ineffective.

The interaction of normal lymphocytes and cells from lymphoid cell lines. II. Variations relating to cell line source and lymphocyte donor

Irradiated LCL cells from several sources activated the blood lymphocytes of a panel of donors. Individual differences were present but were small. Stimulated blood lymphocytes were more potent activators (after X-irradiation) than small lymphocytes in a one-way mixed lymphocyte reaction, indicating that the state of metabolic activity of the `stimulating' lymphocyte affects the level of activation achieved. However, LCL cells incubated for several days after irradiation had not lost stimulatory capacity. Lymphocytes of pigs, rabbits, rats and mice were much less responsive than human lymphocytes. The response of animal lymphocytes generally varied with the species of origin of the serum used in the cultures.