Selection for high and low antibody responses to sheep red blood cells influences cytokine and chemokine expression in chicken peripheral blood leukocytes and splenic tissue

Authors: Swaggerty, Christina - Christi; SIEGEL, PAUL - Virginia Tech; HONACKER, CHRISTA - Virginia Tech; Kogut, Michael - Mike; Anderson, Robin; ASHWELL, CHRISTOPHER - West Virginia University; TAYLOR, ROBERT - West Virginia University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2024
Publication Date: 6/26/2024
Citation: Swaggerty, C.L., Siegel, P.B., Honacker, C.F., Kogut, M.H., Anderson, R.C., Ashwell, C.M., Taylor, R.L. 2024. Selection for high and low antibody responses to sheep red blood cells influences cytokine and chemokine expression in chicken peripheral blood leukocytes and splenic tissue. Poultry Science. 103(9). Article 103972. https://doi.org/10.1016/j.psj.2024.103972.
DOI: https://doi.org/10.1016/j.psj.2024.103972

Interpretive Summary: An important part of an immune response involves antibodies. A line of chickens has been selected for their antibody response for many years, and because of this selection, there are now two lines: a line with high, and a line with low antibody levels. We wanted to know if selecting for antibody levels influences other parts of the immune system including cytokines (chemical messengers). Cytokines are produced by immune cells found in the blood and the spleen. We sampled chickens from the high and low lines and looked at several different cytokine levels in the blood and spleen. Comparing the blood samples, we found one cytokine (IL6) that was different between the two lines, and there was more of it in the low line. When we looked at the cytokine levels in the spleen, we identified other cytokines (IL4 and IL8) that were affected by the selection pressures. In this instance, the high line of chickens had higher levels compared to the low line. This study showed that selection pressures for antibody responses does impact other aspects of the immune response in chickens including cytokine production in the blood and the spleen.

Technical Abstract: Cornell Random bred White Leghorn chickens have been divergently selected for high (HAS) or low (LAS) antibody responses to sheep red blood cells (SRBC) for over 50 generations resulting in two stable lines of chickens. Over the years, much has been studied in these two research lines; however, the impact of these selection pressures on cytokine and chemokine expression is not fully understood. The purpose of this study is to determine if selection for antibody response to SRBC has an impact on cytokine and chemokine expression in peripheral blood leukocytes (PBL) and spleen samples from HAS and LAS chickens. At necropsy, blood (3-5 mL) was collected from chickens from each line (n=36-39) via the brachial vein and placed into vacutainer tubes containing EDTA. Additionally, a piece of spleen (approximately 100 g) was collected and stored in an RNA-stabilizing reagent. Total RNA was isolated from the PBL and spleen samples and the mRNA expression of cytokines (IL4, IL6, IL10, TGF-'4) and chemokines (CXCL8 [IL8], CCL4 [MIP-1beta]) were determined by quantitative real-time RT-PCR (qRT-PCR). The data were analyzed using Student’s t test comparing HAS and LAS (P<0.05) and are reported as corrected 40-CT. The PBL and spleen samples were analyzed separately. With respect to PBL, the mRNA expression of IL6 was higher (P<0.05) in PBL isolated from LAS chickens compared to those from the HAS line while there were no differences in IL4, IL10, CXCL8, CCL4, or TGF-beta4 (P>0.05). The cytokine and chemokine mRNA expression profile were different in the spleen. IL4 and CXCL8 mRNA expression was higher (P<0.05) in spleen samples from HAS chickens compared to LAS. There were no differences in mRNA expression of IL6, IL10, CCL4, or TGF-beta4 (P>0.05) in the spleens from HAS and LAS chickens. The data indicates selection for specific antibody responses to SRBC does impact the cytokine and chemokine expression profile in PBL and spleens differently between each line.