title: Dietary zinc deficiency lowers the proportions of splenic CD90+ (Thy-1+) B-cells and late thymic emigrant T-cells in growing rats.
abstract: Zn-deficient (ZD) rats have a lower proportion of splenic CD90+T-cells which could be due to fewer new T-cells exiting the thymus, defective post-thymic maturation or increased cell death. Post-thymic maturation of splenic lymphocytes and their viability were determined by flow cytometry in weanling rats assigned to ZD ( < 1 mg Zn/kg; ad libitum), diet-restricted (DR; 30 mg Zn/kg; limited to the amount of feed as consumed by ZD rats), marginally Zn-deficient (MZD; 10 mg Zn/kg; ad libitum) or control (30 mg Zn/kg; ad libitum) groups for 3 weeks. ZD rats had a 29 % lower percentage of splenic CD90+T-cells and both ZD and DR rats had a 30 % lower proportion of splenic CD90+B-cells compared with control rats. When the splenic CD90+T-cells were characterised further, there was no difference among the groups in the first two stages of post-thymic development; however, ZD, DR and MZD rats had a 42 % lower proportion of late thymic emigrants (TCRalphabeta+CD90+CD45RC+RT6.1+) compared with control rats. There was no difference among groups in the proportion of splenic CD90+T-cells in the non-viable region; however, ZD rats had a higher proportion of CD90+B-cells in the non-viable region compared with MZD and control animals, suggesting that this phenotype was more susceptible to cell death during deficiency. The lower proportion of splenic CD90+T-cells in ZD rats does not appear to be due to a defect in thymic production or increased cell death in the spleen. Future studies should determine if late thymic emigrants have homed to other peripheral organs.
authors.affiliation: Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Hosea
authors.forename: Edward S
authors.initials: ES
authors.lastname: Rector
authors.forename: Carla G
authors.initials: CG
authors.lastname: Taylor
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000473:pathology; D016923:Cell Death; D004032:Diet; D005434:Flow Cytometry; D018655:Lymphocyte Count; D016131:Lymphocyte Subsets / Q000276:immunology*; D008297:Male; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013154:Spleen / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology / Q000473:pathology; D018800:Thy-1 Antigens / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology*; D015032:Zinc / Q000172:deficiency*
chemical_list: D018800:Thy-1 Antigens; D015032:Zinc