The effect of interleukin 2 and transforming growth factor-beta 2 (TGF-beta 2) on the proliferation and natural killer activity of decidual CD16- CD56bright natural killer cells.

The present study, using flow cytometry, demonstrated that CD16- CD56bright natural killer (NK) cells, which are abundant in the decidua, have both interleukin-2 receptor alpha (IL-2R alpha) and interleukin-2 receptor beta (IL-2R beta). The NK activity and DNA synthesis of CD16- CD56bright NK cells were markedly elevated even by treatment with small amounts of IL-2. These results indicate that decidual CD16- CD56bright NK cells possess a high-affinity receptor for IL-2. Transforming growth factor-beta 2 (TGF-beta 2), which is contained in the decidua and is thought to serve as a major immunosuppressive factor, reduced the NK activity of decidual CD16- CD56bright NK cells, but it hardly affected the IL-2-induced augmentation of the NK activity or DNA synthesis of decidual CD16- CD56bright NK cells. The conclusion has therefore been reached that once IL-2 is produced in the decidua, the IL-2-induced potentiation of the NK activity of decidual CD16- CD56bright NK cells cannot be suppressed by TGF-beta 2.