Murine lymph node-derived stromal cells effectively support survival but induce no activation/proliferation of peripheral resting T cells in vitro

Little is known about the homeostatic mechanisms by which the levels of peripheral lymphocytes are maintained. The survival of naïve T cells in vivo must be maintained by some factors that have not been characterized in an in vitro culture system. In this study, we established a culture system of stromal cells derived from murine lymph nodes and investigated the action of the stromal cells in supporting the survival of resting T cells in vitro. Most of the T cells cocultured with the stromal cells did not die, and the supernatant of cultured stromal cells increase the viability of T cells. This T‐cell survival‐supporting activity was maintained for more than 7 days. Although interleukin (IL)‐4, IL‐6, IL‐7, and interferon‐β also rescued peripheral T cells from spontaneous cell death, medium‐soluble and heat‐sensitive factor(s) derived from the stromal cells supported the survival of T cells more effectively and for a longer time than did these cytokines. T cells maintained in the culture system with the stromal cells appeared to remain in a resting G₀/G₁ state and did not show remarkable DNA synthesis. From these results, it is presumed that some soluble factor(s) other than the tested cytokines that have been identified as supporting T‐cell survival are produced from lymph node stromal cells. These factor(s) play an important role in maintenance of resting T cells.