title: Murine cytomegalovirus infection can enhance hybrid resistance through modulation of host natural killer activity.
abstract: Studies were undertaken to assess the effect of murine cytomegalovirus (MCMV) in two different models involving injection of parental cells into F1 hosts. In both of these systems, MCMV-induced enhancement of hybrid resistance was found. In the first model, parent-into-F1 graft-vs-host reaction, MCMV infection of (C57BL/6 x C3H)F1 (B6C3F1) hosts was found to prevent the GVHR normally induced by injection of B6 parental splenocytes into the F1 hosts. The second model involved injection of parental bone marrow into lethally irradiated B6C3F1 and (C57BL/6 x DBA/2)F1 (B6D2F1) hosts. These irradiated hosts are known to exhibit resistance to engraftment by parental C57BL/6 (B6) bone marrow. This resistance was found to be markedly enhanced by injection of the hosts with MCMV 3 days before irradiation and bone marrow injection. In contrast, engraftment into B6C3F1 hosts of syngeneic marrow, or bone marrow from the C3H parent, was not affected by MCMV infection. Engraftment of DBA/2 marrow into B6D2F1 hosts was reduced at lower doses of injected marrow, suggesting enhanced resistance against the minor Hh Ag Hh-DBA. To test whether the MCMV-induced enhancement of resistance was mediated by NK cells, splenic NK activity (YAC-1 killing) and frequency (NK1.1 staining) were assessed. Both parameters were found to be elevated at 3 days after MCMV infection but to return to normal levels by 9 days. B6 bone marrow engraftment was in fact found to be normal when the marrow was administered to F1 mice 9 days after MCMV infection. Furthermore, anti-asialoGM1 administration prevented MCMV-induced enhancement of resistance to marrow engraftment. Thus, the NK enhancement resulting from MCMV infection appears to play a major role in the enhanced HR observed in the marrow engraftment model. This effect may be of importance in clinical bone marrow transplantation, a situation in which patients are susceptible to viral infection.
authors.affiliation: Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: S C
authors.initials: SC
authors.lastname: Muluk
authors.forename: F T
authors.initials: FT
authors.lastname: Hakim
authors.forename: G M
authors.initials: GM
authors.lastname: Shearer
mesh_terms: D000818:Animals; D016026:Bone Marrow Transplantation; D003586:Cytomegalovirus Infections / Q000276:immunology*; D005677:G(M1) Ganglioside; D006028:Glycosphingolipids / Q000502:physiology; D006084:Graft Rejection; D006087:Graft vs Host Reaction; D007694:Killer Cells, Natural / Q000276:immunology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains
chemical_list: D006028:Glycosphingolipids; D005677:G(M1) Ganglioside; C018835:asialo GM1 ganglioside