The mature R3 NK cells from aged mice are intrinsically defective in their ability to home to the D-LN. (A) Purified NK^A and NK^Y cells were labeled with 4 µM and 0.2 µM CFSE (to allow detection of both populations in the same mouse) and cotransferred in equal numbers into young B6 mice. 1 d later, the mice were infected with ECTV and the NK cell responses determined on 2 dpi as indicated at the top of the figure. The top shows representative flow cytometry data gated on the NK1.1⁺CD3⁻ NK. The bar graph on the right shows mean ± SD for the ratio in D-LN versus ND-LN for NK^Y and NK^A cells. Top middle panels are gated on CFSE⁻ host NK cells. Bottom middle panels are gated on transferred NK^Y cells. Bottom panels are gated on transferred NK^A cells. Data are representative of three similar experiments. (B) R1-R3 NK^Y cells from B6-CD45.1 mice were sorted with a flow cytometer (left) and adoptively transferred into young B6 (CD45.2) mice. The next day, the mice were infected with 3,000 PFU ECTV and the migration of the transferred cells to D-LN and ND-LN was determined 2 dpi. The left plot shows the NK^Y cells before sorting. For each type of LN, the plots on the left were gated on NK1.1⁺CD3⁻ NK cells and the box shows the transferred cells. For each type of LN, the plots on the right are gated on the transferred cells. For each type of LN, the top, middle, and bottom panels are for mice transferred with R1, R2, and R3 cells, respectively. Note the relative increase of R3 cells in the D-LN as compared with the ND-LN. Data are representative of three similar experiments.