Figure 4. Commensal bacteria are partially responsible for homeostatic proliferation of NK cells and induction of KLRG1 expression.

(A) Enriched WT (CD45.1⁺) NK cells were labeled with CellTrace Violet and 5 × 10⁵ cells were transferred via intravenous injection into WT mice (CD45.2⁺), Tcra^−/− mice (CD45.2⁺), or Rag1^−/− mice (CD45.2⁺) and given either control or Abx-treated water for 14 days prior to transfer. (B) CellTrace-Violet-labeled WT NK cells were transferred into WT mice (CD45.2⁺), Rag1^−/− mice (CD45.2⁺), or Rag1^−/−Nod2^−/− mice (CD45.2⁺). KLRG1 expression and dilution of CellTrace-Violet in splenic CD45.1⁺ NK cells were analyzed 7 days after transfer. Data are representative of three independent experiments with 3 mice in each experiment. See also Figure S4.