NK cells are severely reduced in Stat5^f/fNcr1-iCreTg mice. Deletion of Stat5 results in severely diminished NK-cell numbers. (A,D) Flow cytometry of Stat5^f/fNcr1-iCreTg mice and littermate controls. Dot plots indicate the percentage of (A) peripheral NK cells (CD3⁻NKp46⁺) and (D) CD4 and CD8 expression on cells from various lymphoid organs. Cells were gated on total thymocytes (top panel), CD3⁺ lymph node cells (middle panel), and CD3⁺ splenocytes (bottom panel). (B) Bar graphs show the percentage of peripheral NK cells (CD3⁻NKp46⁺). (C) Bar graphs show the total splenic (left) and lymph node (right) NK-cell numbers. (E) Bar graphs show the CD4-to-CD8 ratio of total thymocytes (left panel), CD3⁺ lymph node cells (middle panel), and CD3⁺ splenocytes (right panel). (A,D) Data are representative of 3 independent experiments (n ≥ 4 per genotype). (B,C,E) n ≥ 5 per genotype.