NK cells are deficient in the spleens of flt3L−/− mice.

(A) The number of NK1.1⁺⁺ CD3⁻ NK cells present in the spleens of flt3L+/+ and flt3L−/− mice (n = 14) was calculated from the percentage of NK cells detected by flow cytometry combined with splenic cellularity. Data are presented as the mean ± SD. *P < .0001. (B) Mice were injected intraperitoneally with either PBS or 100 μg poly-I:C. The following day spleens were harvested and a cell suspension prepared (effector cells). Serial dilutions of effector cells were cultured for 4 hours with ⁵¹Cr-labeled Yac-1 lymphoma cells (targets). Percent specific lysis of the target cells was estimated as described in “Materials and methods”; • indicates flt3L+/+, poly-I:C treatment; ▪, flt3L+/+, PBS treatment; ○, flt3L−/−, poly-I:C treatment; □, flt3L−/−, PBS treatment. Data shown are representative of data generated from 18 mice.