title: Altered ex vivo cytokine production in zinc-deficient, pair-fed and marginally zinc-deficient growing rats is independent of serum corticosterone concentrations.
abstract: The objective of the present study was to examine the effects of dietary Zn deficiency on the ex vivo cytokine production (IL-2, interferon-gamma (IFN-gamma), IL-6 and IL-10) of isolated thymocytes and splenocytes after mitogenic stimulation with concavalin A and to explore the role of corticosterone in this regulation. Weanling rats were assigned to one of four dietary treatments for 3 weeks: Zn-deficient (< 1mg Zn/kg diet, ad libitum), pair-fed (30 mg Zn/kg diet, limited to amount of feed as consumed by the Zn-deficient group), marginally Zn-deficient (10 mg Zn/kg diet, ad libitum) and control (30 mg Zn/kg diet, ad libitum). Thymocytes and splenocytes were isolated for cytokine stimulation and determination of T-cell phenotypes. Serum corticosterone concentrations were determined by ELISA. The Zn-deficient and pair-fed groups had 14-fold higher serum corticosterone concentrations compared with the marginally Zn-deficient and control groups (P<0.0001). The proportions of thymocyte subsets were not altered in the Zn-deficient, pair-fed or marginally Zn-deficient groups; however, thymocyte IL-2 and IL-6 production in these groups was 33-54% lower compared with the control group (P<0.05). The Zn-deficient group had an 18-28% lower proportion of new T-cells (TCRalphabeta+CD90+), but no difference in the proportion of new T-cells that were cytotoxic or helper. The Zn-deficient group had a 49-62% lower production of Th1 cytokines (IL-2), but no difference in the production of Th2 cytokines (IL-6, IL-10) by stimulated splenocytes compared with the pair-fed, marginally Zn-deficient and control groups (P<0.01). These results indicate that Zn status is associated with altered cytokine production, while in vivo corticosterone concentrations are not associated with ex vivo cytokine production.
authors.affiliation: Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, AB T6G2P5, Canada.
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Hosea Blewett
authors.forename: Edward S
authors.initials: ES
authors.lastname: Rector
authors.forename: Carla G
authors.initials: CG
authors.lastname: Taylor
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D003345:Corticosterone / Q000097:blood*; D016207:Cytokines / Q000276:immunology*; D004032:Diet; D005269:Femur / Q000737:chemistry; D005434:Flow Cytometry; D007371:Interferon-gamma / Q000032:analysis; D016753:Interleukin-10 / Q000032:analysis; D007376:Interleukin-2 / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D013154:Spleen / Q000276:immunology / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology / Q000473:pathology; D014886:Weaning; D015032:Zinc / Q000032:analysis / Q000097:blood / Q000172:deficiency*
chemical_list: D016207:Cytokines; D007376:Interleukin-2; D015850:Interleukin-6; D003208:Concanavalin A; D016753:Interleukin-10; D007371:Interferon-gamma; D015032:Zinc; D003345:Corticosterone