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.

In each of the seven experiments, elevated pathology was observed in MCMV-infected mice depleted of 1F8 Ï© cells, in comparison to infected, nondepleted controls. Spleens from mAb 1F8-treated mice were smaller in size and had lower cell counts than in MCMV-infected control mice, typical of enhanced MCMV pathology. In three experiments harvested at day 3 after infection, half spleen (the other half was used for viral titrations) leukocyte counts in control-infected mice were 6.6 Ï® 1.3 Ï« 10 7 (n Ï­ 15), whereas those in infected mAb 1F8-treated mice were 3.8 Ï® 1.5 Ï« 10 7 (n Ï­ 15), P = .000007, by Student's twotailed t test. In three experiments harvested at day 4 after infection, (experiments 1, 3, and 4; Table II ), half spleen leukocyte counts for infected-control mice were 7.0 Ï® 1.3 Ï« 10 7 (n Ï­ 13), whereas the counts in mAb 1F8-treated infected mice were 3.2 Ï® 1.3 Ï« 10 7 (n Ï­ 14), P Ï­ .0000002. Infected mice treated with mAb 5E6 (Exp. 1, Table II ) did not have reduced leukocyte counts when compared with infected controls. These dramatic and (Ly49C/I/H), anti-Ly49G2, or a mAb isotype control. In this case they were also costained with mAb to CD8 (as part of an experiment examining both T and NK cell functions), so the NK1.1 Ï© cells may include both NK and NK/T cells. This figure shows selective depletions of some of the Ly49 subsets due to this mAb treatment. These same mice were examined for viral load, and those data are listed in experiment 1 (Table II) . highly significant reductions in spleen leukocyte count in the mAb 1F8-treated mice are consistent with the dramatic elevations in spleen MCMV titers observed in those mice.