title: T lymphocyte subpopulations diverge in commercially raised chickens.
abstract: To evaluate immunocompetence in commercially raised chickens, we immunophenotyped Dekalb Delta and H&N White Leghorn (WLH) hybrids, 20 chickens in each of 3 age groups (9 wk [juvenile], 25 wk [young adult], and 79 or 80 wk [adult]), for circulating CD3+, CD4+, CD8+, TCR1+, TCR2+, and TCR3+ lymphocytes. The proportion of CD3+ T cells, including CD4+ and CD8+ subsets, was increased in the hybrids as compared with published values for laboratory-raised outbred WLH chickens. The proportion of the TCR2+ (Vbeta1) T cell subpopulation was also increased. An age-related decrease in the proportion of TCR1+ (gammasigma) T cells was noted in both hybrids. Further, a remarkably low CD4:CD8 ratio was evident in all age groups of both hybrids, indicating decreased immunocompetence. Overall, these experiments provide age-related proportions of various peripheral-blood T lymphocyte subpopulations in commercially raised Dekalb Delta and H&N chickens that diverge from the proportions in laboratory-raised outbred WLH chickens and suggest reduced immunocompetence. Such a decline in immunocompetence, including humoral immune capacity, could be attributed to genetic selection for production traits, environmental factors associated with commercial operations, and intense immunization.
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph.
authors.forename: Byram W
authors.initials: BW
authors.lastname: Bridle
authors.forename: Richard
authors.initials: R
authors.lastname: Julian
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Shewen
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Vaillancourt
authors.forename: Azad K
authors.initials: AK
authors.lastname: Kaushik
mesh_terms: D000367:Age Factors; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D016516:CD4-CD8 Ratio / Q000662:veterinary; D002645:Chickens / Q000235:genetics / Q000276:immunology*; D003433:Crosses, Genetic; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D007121:Immunocompetence; D018655:Lymphocyte Count / Q000662:veterinary; D008297:Male; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal