Lymphoblastoid cell lines are polyclonal activators of human T lymphocytes.

Following stimulation with autologous or allogeneic lymphoblastoid cell lines (LCL) human T lymphocytes acquire two properties which suggest that LCL act as polyclonal activators. Cytotoxic activity, which has an antigen-specific component, is produced towards normal lymphocytes and LCL, and the cells become capable of mounting proliferative responses to antigens on human B lymphocytes which have accelerated secondary-type kinetics. Only weak responses to autologous cells occur. In addition, repeated restimulation with the original LCL leads to a progressive increase in the number of cells in the culture for a period of about 4 weeks. This approach may prove a useful way to grow large numbers of human T lymphocytes for further study.