Effect of acute heat stress on calcium concentration, proliferation, cell cycle, and interleukin-2 production in splenic lymphocytes from broiler chickens

• Published in: Poultry science 2010-10, Vol.89 (10), p.2063-2070
• Main Authors: Han, A.Y, Zhang, M.H, Zuo, X.L, Zheng, S.S, Zhao, C.F, Feng, J.H, Cheng, C
• Format: Article
• Language: English
• Subjects: Animals; body temperature; breathing; broiler chickens; calcium; Calcium - metabolism; CD4-positive T-lymphocytes; CD8-positive T-lymphocytes; Cell Cycle; Cell Proliferation; cell-mediated immunity; corticosterone; flow cytometry; heat stress; Hot Temperature; interleukin-2; Interleukin-2 - genetics; Interleukin-2 - metabolism; Lymphocyte Subsets - classification; Lymphocyte Subsets - cytology; Lymphocyte Subsets - metabolism; lymphocytes; Male; mineral content; protein secretion; spleen; Spleen - cytology; Stress, Physiological
• ISSN: 0032-5791; 1525-3171
• DOI: 10.3382/ps.2010-00715

In the present study, we investigated the effects of acute heat stress on the concentration of free Ca²⁺ ([Ca²⁺]i) and markers of cellular immunity in splenic lymphocytes from broiler chickens. Eighty 6-wk-old male broilers were randomly allocated to 2 treatments and exposed to 25 and 35°C (RH, 50 ± 5%) for 3 h. We observed that 3 h of heat exposure (35 ± 1°C, 50 ± 5% RH) increased the body temperature and respiratory rate of broiler chickens significantly, but plasma levels of corticosterone were not changed. Examination of [Ca²⁺]i and the proliferation of splenic lymphocytes isolated from heat-stressed broiler chickens, using fura-2-acetoxymethyl ester and Cell Counting Kit-8, respectively, showed that acute heat stress caused a significant increase in [Ca²⁺]i and enhanced concanavalin A-stimulated but not lipopolysaccharide-stimulated lymphocyte proliferation significantly. Flow cytometric analysis of the cell cycle and T-lymphocyte subsets (CD4⁺ and CD8⁺) indicated that heat stress promoted the transition of lymphocytes from gap phase 1 to synthesis phase and increased the ratio of CD4⁺ to CD8⁺ of T lymphocytes. In addition, acute heat stress enhanced the secretion of interleukin-2 by splenic lymphocytes significantly. These results suggest that the effect of acute heat stress to increase the [Ca²⁺]i in lymphocytes may be an early event that enhances Con A-stimulated T-cell proliferation and interleukin-2 secretion and promotes the transition of T cells from gap phase 1 to synthesis phase.