Our outcomes indicate that CR exacerbates the detrimental ramifications of aging in NK cell amounts and phenotype that could donate to increased threat of viral infection. 2. limitation either at the typical 12 weeks old or at 78 weeks old. NK cells were quantified and isolated from different tissue using movement cytometry. Aged CR mice got considerably reduced degrees of terminally older (Compact disc27?Compact disc11b+) NK cells, increased appearance from the immature marker Compact disc127, and decreased appearance from the mature marker DX5. Final number of NK cells among cells was considerably low in the lung and spleen of old-onset aged CR mice in comparison to aged AL mice, while there is no factor between young-onset aged CR and aged AL mice. Old-onset aged CR mice had significantly less early mature (DX5+ and CD27+CD11b+) NK cells compared to young-onset aged CR and aged AL fed mice. Overall, we found that CR in aged mice is detrimental to maturation of NK cells, which is exacerbated when CR is initiated in old-age. (AL) fed aged mice infected with influenza had decreased NK cell survival  and functional responses  compared with adult mice. The phenotype of NK cells from aged CR mice has yet to be characterized. Age of CR onset is important for development of immune benefits associated with CR. Messaoudi showed that initiating CR in young adult (postpuberty) primates prevents T cell senescence associated with aging, while young-onset (pre-puberty) CR and old-onset CR had a detrimental effect on T cell development and function . However, when CR was initiated in young adult mice, NK cells did not mature completely nor develop their full function . Due to different effects of CR on NK cells compared to T cells when initiated in young adult animals, it is possible that age of onset affects NK cells differently than T cells. While we have described B-HT 920 2HCl NK cell changes in adult CR mice and observed increased susceptibility to primary influenza infection in aged CR mice, we have yet to determine if this increased susceptibility of aged CR mice to influenza was related to alterations in NK cell maturation or function. In the present studies, we evaluated NK cell number and phenotype in aged (22 month) C57Bl/6 mice consuming a CR diet. Based on our previous observations regarding aging and CR, we hypothesized there would be more NK cell phenotypic differences in aged CR mice compared with controls. In addition, CR may affect NK cells differentially depending on the age of the animals at the time of CR initiation. Therefore, the second aim of our study was to determine whether adult-onset CR affects NK cells differently than old-onset CR in aged mice. We hypothesized the age of onset of CR would not have different effects on NK cell maturation. Our results indicate that CR exacerbates the detrimental effects of aging on NK cell numbers and phenotype which could contribute to increased risk of viral infection. 2. Methods and Materials 2.1 Animals and housing C57Bl/6 male mice Rabbit Polyclonal to BCAS2 were purchased from the National Institute of Aging (NIA) maintained at Charles River Laboratories (Wilmington, MA, USA). Mice were individually housed in micro-isolator cages at the Michigan State University Research Containment Facility, a facility certified by the Association for Assessment and Accreditation of Laboratory Animal Care International. Mice were fed diets purchased from the NIA. Control animals received NIH-31 diet AL, and calorie restricted (CR) animals received 3 g/day of NIH-31/NIA fortified diet, resulting in 40% CR (Table 1). These diet compositions have been described previously . Body composition was measured weekly using an EchoMRI-500 (Echo Medical Systems, Houston, TX, USA) as previously described B-HT 920 2HCl . Mice were euthanized by CO2 asphyxiation followed by cardiac puncture. All animal procedures were in accordance with the National Research Council guidelines and approved by the Michigan State Institutional Animal Care and Use Committee. Table 1 Macronutrient and nutrient content of the diets fed to mice test to determine the effects of age, diet, and agediet interaction on NK cell phenotype. Data comparing age of onset (A-AL, Y-A-CR, and O-A-CR) was analyzed using one way ANOVA followed by Tukeys test to determine the effects of CR onset on NK cell phenotype. All B-HT 920 2HCl data are expressed as means SEM and.