NK-cell–mediated control of spontaneous metastasis by independent pfp and IFN-γ activities.

BALB/c, BALB/c.SCID, BALB/c.IFN-γ⁰, BALB/c.pfp⁰, and BALB/c pfp⁰.IFN-γ⁰ mice or BALB/c mice treated with anti-asialo GM1 antibody (100 μg/injection) were inoculated subcutaneously with DA3 tumor cells (10⁵ or 5 × 10⁵) as indicated. Mice depleted of subsets in vivo were treated on days −4, 0 (day of subcutaneous tumor inoculation), and weekly thereafter. Forty-two days after tumor inoculation, the lungs of these mice were harvested and fixed, and colonies were counted and recorded as the mean number of colonies ± SE. Asterisks indicate the groups that are significantly different from BALB/c-untreated mice (*P < .0001; **P < .005; Mann-Whitney U test). A significant difference was also detected between the BALB/c.P⁰ mice or BALB/c.IFN-γ⁰ mice and BALB/cP⁰.IFN-γ⁰ mice (P < .0001). The number of mice per group is shown in parentheses. Note that for groups of 5 mice receiving 10⁵DA3 tumor cells, the numbers of DA3 lung colonies were as follows: BALB/c.B6Cmv1^r = 8.0 ± 2.6; BALB/c.B6Cmv1^r + anti-asialo GM1 antibody = 62.4 ± 6.6.