H. Suzuki et al., Normal regulatory alpha/beta T cells effectively eliminate abnormally activated T cells lacking the interleukin 2 receptor beta in vivo, J EXP MED, 190(11), 1999, pp. 1561-1571
Although interleukin 2 (IL-2) has been thought to be the most important cyt
okine for T cell growth, animals lacking IL-2 or a component of its recepto
r molecules have more expanded T cells with activated memory phenotype, ind
icating an indispensable role for the IL-2/IL-2 receptor system in regulati
ng the size and activity of the T cell population. In this study, we invest
igated the possible mechanism of abnormal expansion of activated T cells in
IL-2 receptor beta chain (IL-2R beta)(-/-) mice using the systems of bone
marrow transplantation and T cell transfer. Here, we show that IL-2R beta(-
/-) T cells in mice reconstituted with a mixture of IL-2R beta(-/-) and IL-
2R beta(+/+) bone marrow cells did not develop into an abnormally activated
stage, and that already activated IL-2R beta(-/-) T cells were effectively
eliminated by IL-2R beta(+/+) T cells when both cells were cotransferred t
o T cell-deficient host mice. This regulation and/or elimination was depend
ent on T cells bearing alpha/beta type T cell receptor, especially on CD8() T cells and independent of the Fas-Fas ligand (FasL) system. IL-2R beta(/+) T cells that eliminated activated IL-2R beta(-/-) T cells expressed Fas
t, perforin, granzyme B, and tumor necrosis factor alpha/beta. These result
s indicate a novel function of IL-2R beta that is necessary for the inducti
on of regulatory T cells acting to eliminate activated T cells.