University of Arkansas, Fayetteville Division of Agriculture


poultry, immune cells, hypothyroidism


The Obese strain (OS) of chickens spontaneously develops autoimmune thyroiditis (SAT) and is a well-established biomedical model for Hashimoto’s thyroiditis in humans. Both conditions are characterized by the infiltration of thyroid glands with mononuclear immune cells resulting in the destruction of thyroid tissue and impairment of the thyroid’s endocrinological functions. Past studies described immune cell infiltration in thyroids of the OS chickens, but the time-course, cell composition, and relative amounts of the various immune cells infiltrating the thyroids have not been well defined. In this project, frozen and stored thyroid glands that were previously collected at 1, 4, 7, 14, 21, 28, 35, and 42 days of age (n = 4 to 5 OS birds/age) were used. Frozen thyroid sections (8-μm thick) were prepared and used in an indirect immunohistochemical staining procedure to identify macrophages, B cells, T cells, T helper cells, cytotoxic T cells, γδ T cells, and MHC II-expressing cells. Stained sections were evaluated by microscopy, and the percentage of tissue area occupied by various cell types was determined. Thyroid infiltration was first observed at 7 days of age, and immune cells occupied the entire tissue in most samples from 3 weeks onwards. Macrophages were the first cells to infiltrate, but T cells dominated the response. MHC II expression reached very high levels by 14 days and remained at nearly 100% thereafter. This study provided new insights regarding the participating immune cells and the chronological order of their infiltration into thyroid glands during SAT development in OS chickens.