Figure 4. Arrested maturation of NK cells exacerbates lung tumor engraftment, but has minimal impact on liver tumor load.

Wild type or Ly49A transgenic mice were treated with control mouse immunoglobulin, or depleted of NK cells using mAb PK136. 3×10⁵ B16F1 melanoma cells were injected i.v., and mice were euthanized 14 days later for enumeration of tumor burden. Ly49A Tg mice develop more pulmonary tumor nodules than wild type littermates. Elimination of NK cells does not significantly increase the number of tumor nodules in the lung. In contrast, Ly49A Tg mice develop a similar number of liver tumor nodules as wild type controls, indicating that the immature hepatic NK cells confer substantial protection against tumor establishment in this organ.