Cytotoxic activity of NK cells in the fetal liver and spleen. FACS profiles of CD122 and NKp46 co-expression in (A) liver and (B) spleen in 14.5- to 18.5-day-old fetuses. BM and spleen cells from adult mice were used as a positive control. Numbers in FACS profiles indicate the mean frequencies of populations within the indicated gates. Text above plots indicates gating. Data from representative analysis, 3-5 fetuses were analyzed from 2 to 3 different litters; 2 spleens were pooled for the analysis. FACS profiles of CD107a expression by Lin⁻CD3⁻CD122⁺DX5⁺NKp46⁺ NK cells after activation with purified anti-NK1.1 Ab in (C) liver and (D) spleen cells in 14.5- to 18.5-day-old fetuses. Nonactivated cells were used as negative control, and cells from the adult spleen were used as positive control. Numbers in FACS profiles show frequencies of populations within the indicated gates of total cells. Data from one representative experiment with the use of cells from 2 litters, 3 replicates were performed, all giving similar results.