Effects of Age and Gonadal Steroids on the Localization of T Cell Subsets in the Epididymis of Male Chickens, Gallus domesticus

Abstract

The aim of this study was to examine the effects of age and gonadal steroids on the localization of T cell subsets in the epididymis of roosters in order to determine the factors affecting their populations. Immature and matured White Leghorn male birds were used, and some of the immature birds were i.m. injected daily with 1mg testosterone propionate (TP), 1mg estradiol benzoate (EB) or 100μl of sesame oil (control) for 3 or 6 days. Cryostat sections of their epididymis were immunostained for CD4 or CD8 antigens. Many of the CD4⁺ and CD8⁺ T cells were found in the subepithelial layer of efferent ductules and epididymal duct and also in the interstitum in matured and immature birds. The frequencies of CD4⁺ and CD8⁺ T cells in the subepithelial layer of efferent ductules and interstitum was significantly greater in matured birds than in immature ones. The ratios of CD4⁺/CD8⁺ T cells in the efferent ductules and interstitum were not different between matured and immature birds. In the subepithelial layer of efferent ductules of immature birds, the frequencies of CD4⁺ and CD8⁺ T cells were significantly increased by Day 3 of TP-injection, followed by a decrease to the level of Day 0 by Day 6. Their frequencies were increased by EB-injection on Day 3 and 6 compared with Day 0. In the interstitum of TP-injected birds, the frequency of CD4⁺ T cells were not changed until Day 6, whereas CD8⁺ T cells increased on Day 3 and Day 6 compared with Day 0. Injection with EB caused a significant increase of both CD4⁺ and CD8⁺ T cells on Day 3 and Day 6 compared with Day 0. The CD4⁺/CD8⁺ T cells ratio in the epididymal subepithelial layer and interstitum were not significantly different among treatment days within control, TP- and EB-injected groups. These results suggest that the populations of CD4⁺ and CD8⁺ T cells in the epididymis are increased in the matured birds compared with immature ones, and luminal contents and gonadal steroids may be responsible in the increase of those T cells.