Bovine T lymphocytes. I. Generation and maintenance of an interleukin-2-dependent, cytotoxic T-lymphocyte cell line.

Primary and secondary bovine allogeneic mixed leucocyte cultures were examined for the generation of antigen-specific cytotoxic leucocytes. While optimal generation of murine and human cytotoxic T lymphocytes typically requires 4-8 days, alloantigen-specific cytotoxic bovine leucocytes were demonstrated consistently only after prolonged incubation periods, optimally found to be about 15 days. Restimulation of long-term bovine mixed leucocyte cultures with the original stimulator population revealed responder cells demonstrating augmented alloantigen-specific lytic activity. When placed into human recombinant interleukin-2, responder cells expanded and required passaging every 3-4 days. The same was not true of cells placed into interleukin-2-free medium. Cells cultured in interleukin-2-containing medium retained alloantigen specificity after 10 weeks of culture. Moreover, they continued to display total dependence on human, simian or bovine interleukin-2 for growth.