Interferon‐γ production by Listeria monocytogenes‐specific T cells active in cellular antibacterial immunity

Cultures of peritoneal exudate T lymphocyte-enriched cells (PETLEC) from Listeria monocytogenes-immune mice, antigen-presenting cells (APC) and heat-killed L. monocytogenes produced high amounts of interferon-gamma (IFN-gamma). High IFN titers were also observed after stimulation of L. monocytogenes-immune cell cultures with the T cell mitogens concanavalin A and phytohemagglutinin. L. monocytogenes-immune PETLEC produced several fold higher IFN titers than normal cell cultures in response to mitogen and antigen. Under both circumstances, APC were required for optimum responses. L. monocytogenes-immune PETLEC participating in IFN production were Lyt 1+23-. IFN-gamma was also produced in cultures of cloned L. monocytogenes-specific T cells. Since the same T cell clone showed antigen-specific proliferative responses and interleukin production in vitro, and could adoptively mediate delayed-type hypersensitivity and anti-listerial protection in vivo, it is suggested that IFN production is a function of specific T cells active in cellular antibacterial immunity.