Effects of Repeated Lipopolysaccharide Stimulation on the Development of Antigen-presenting Cells and T Cells Pool in Hen Vagina

Abstract

The aim of this study was to determine how the mucosal immunity mediated by T cells is developed in the vagina. Antigen-presenting cells and T cells play important roles in the early process of host defense. Mature T cells and immature dendritic cells expressing CC chemokine receptor (CCR) 6. In contrast, immature T cells and mature dendritic cells express CCR7. It was examined whether repeated antigen stimulation is effective for development of the pool of antigen-presenting cells and T cells in the vagina. White Leghorn hens were intravaginally injected 1 (single injection group) or 5 times (repeated injection group) in 10 days with saline (control) or lipopolysaccharide (LPS). The vagina was collected 1 day after the final injection. Frozen sections of them were immunostained for CD4+, CD8+, TCRγδ+ T cells and major histocompatibility complex (MHC) class II+ cells. Expressions of CCR6, CCR7 and MHC class II were analyzed by quantitative RT-PCR. The frequency of CD4+, CD8+, TCRγδ+ T cells were significantly increased in LPS-repeated injection group, however that of MHC class II+ cells was not changed significantly. The expression of CCR6 was significantly upregulated in LPS-repeated injection group, however, the expression of CCR7 and MHC class II was not affected. The densities of the each T cell subset and MHC class II+ cells, as well as expressions of chemokine receptor, MHC class II were not affected by single LPS injection or saline injection. These results suggest that the repeated antigen stimulation may not affect antigen-presenting ability by antigen-presenting cells, whereas it may lead influx of T cell subsets in the vagina. These accumulated T cells pool may contribute to form prequiescence of host immunity in the vaginal mucosa.