Murine Cytomegalovirus Is Regulated by a Discrete Subset of Natural Killer Cells Reactive with Monoclonal Antibody to Ly49h

Daniels, Keith A.; Devora, Gene; Lai, Wayne C.; O'Donnell, Carey L.; Bennett, Michael; Welsh, Raymond M.

MCMV Titers in Mice Depleted of 1F8 ϩ NK Cells. Depletion of the 1F8 ϩ but not the 5E6 ϩ NK cell population before infection with MCMV led to 20-1,000-fold increases in spleen MCMV titers by day 3 or 4 after infection. Five experiments, one with T cell KO mice, are shown in Table II , illustrating this important point. Experiment 1 shows the titers in the same mice portrayed in Fig. 7 . Here treatment with mAb 1F8 resulted in Ͼ100-fold increases in MCMV titers in the spleen and eightfold increases in the liver. Treatment with mAb 5E6 did not significantly elevate spleen titers, confirming our previous report (22) . In fact, we previously showed that treatment of mice with mAb 5E6 in combination with mAb to Ly49D or Ly49G2 also did not enhance MCMV titers in comparison to mice treated only with the HBSS vehicle (these experiments also serve as good Ab injection controls; reference 22). In experiment 2, treatment with mAb 1F8 is compared with mAb to NK 1.1, which depletes virtually all NK cells. MCMV titers were slightly but not substantially higher in anti-NK1.1 treated-versus mAb 1F8-treated mice. In experiment 4, mice were inoculated with only 50 g of mAb 1F8, which still manifested a profound effect, and in experiment 5 T cell KO mice were inoculated with 25 g of mAb and developed 100-fold increases in spleen titers. In all, a total of seven experiments showed elevated MCMV titers in mAb 1F8-treated mice.