Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Agriculture

Degree Level

Undergraduate

Department

Poultry Science

Advisor/Mentor

Graham, Danielle

Committee Member

Erf, Gisela

Second Committee Member

Santamaria, Jossie

Third Committee Member

Weimer, Shawna

Abstract

In chickens, the growing feather (GF) pulp has been established as a cutaneous bioassay to monitor and assess tissue/cellular immune activities in response to intradermal (i.d.) injections of test materials. The objective of this pilot study was to determine the suitability of the GF bioassay in turkeys by examining the acute inflammatory responses initiated by i.d. GF-pulp injections of lipopolysaccharide (LPS). For this, three, 5-wk-old turkey poults were used. Two poults had 8 GFs injected (10 μL/GF) with low (L)-LPS (0.1 μg/GF) and 8 GFs with high (H)-LPS (1 μg/GF), while a third poult had 8 GFs injected with endotoxin-free PBS and 9 GFs with H-LPS. Heparinized blood and GFs were collected before (0h) and at 3h and 6h post GF-pulp injection. Blood and pulp cell suspensions were stained with a panel of chicken leukocyte-specific fluorescence-conjugated antibodies with cross-reactivity for turkey cells to identify total leukocytes, heterophils, MHC II+ cells, B cells, and T cell subsets by flow cytometry analysis. Two-way ANOVA was used to test the effects of LPS dose, time, and their interactions on leukocyte profiles in GFs, and one-way repeated measures ANOVA to test the effect of LPS on blood leukocyte (WBC) profiles over time. Tukey’s HSD test was conducted when appropriate. Significance was set at P ≤ 0.05. In GFs, both L-LPS and H-LPS stimulated leukocyte-infiltration, primarily heterophils, by 3h p.i., reaching maximal levels (% pulp cells) at 6h (P ≤ 0.05), but did not affect levels of MHCII+-, CD4+-, and CD8+--cells. However, L-LPS triggered a marginally higher αβ T cell recruitment (P = 0.052) than H-LPS. PBS also recruited heterophils but at lower levels than LPS. In the blood, i.d. LPS injection resulted in a doubling (P ≤ 0.05) of heterophil concentrations by 6h p.i., caused a transient drop in concentrations of WBC, CD4+ T cells and αβ T cells at 3h (P ≤ 0.05), but did not affect those of CD8+ T cells. For the proportions among blood leukocytes, i.d. GF-pulp injection of LPS caused an increase in % heterophils (P = 0.037), and a drop in % monocytes (P = 0.032) and % lymphocytes (P = 0.013) by 3 h and remained near these levels by 6 h p.i. There was not an effect of time on the percentage of eosinophils and basophils, however, a marginal effect of time (P = 0.090) was observed on the heterophil to lymphocyte ratio characterized by an increase at 3 h and 6 h p.i. This pilot study highlights the similarities in the inflammatory responses initiated by LPS in turkeys and chickens and demonstrates the applicability of the two-window (GF and blood) approach to study local and systemic immune system responses in turkeys. A study is underway to further assess the inflammatory response to LPS from its initiation to resolution in turkeys.

Keywords

Turkeys, Lipopolysaccharide, Inflammatory Response, Leukocytes, Cutaneous Bioassay

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