Background: Lymph node stromal fibroblasts are interconnected with TCD4+ cells and affect their phenotype and function. Understanding the nature of these interactions under unusual conditions like infections will help to their application in control and regulation of immune responses.

Materials and methods: Lymph node fibroblasts were affected in BCG primed immune environment by both in-vitro and in vivo method. Fibroblasts isolated through enzymatic digestion and surface markers and co-cultured with spleen isolated naive T cells for 72-hours in a cell-to-cell contact manner. Then naive T cells were removed and cultured 72-hours more and assessed for regulatory T cell marker expression and IL-4, TGF-β1, IL-10 and IFN-γ cytokine production.

Results: Results showed that in in-vivo stimulation method, more regulatory T cells was induced by BCG stimulated fibroblasts compared to non-stimulated fibroblasts. In this method, IFN-γ cytokine production was reduced and IL-10 and TGF-β1 regulatory cytokine production was increased. In contrast, in in-vitro stimulation method, regulatory T cell induction by BCG stimulated fibroblasts was significantly less than non-stimulated ones. In addition, both IL-10 and IFN-γ production was increased that indicate induction of IFN-γ producing T-cells.

Conclusion: Present study shows that fibroblasts affect regulatory T-cell induction and T-cell function. The result of this effect is dependent to environment. In this study, fibroblasts were isolated from two different BCG stimulated immune environment. They induced more regulatory responses in in-vivo condition and reduced regulatory responses in in-vitro environment. This result demonstrates different fibroblast behavior at different phases of infection.