Anti-Interferon-gamma Autoantibodies Impair T-Lymphocyte Responses in Patients with Talaromyces marneffei Infections

Background: Although anti-IFN-gamma autoantibodies predispose patients to Talaromyces marneffei infection, whether this is mediated by T cell attenuation remains elusive. Methods: Total peripheral blood mononuclear cells (PBMCs) from healthy donors or patients with T. marneffei infection were stimulated with M1(58-66), and immunodominant influenza H1N1 peptide, or heat-inactivated T. marneffei in the presence of serum from anti-IFN-gamma autoantibody-positive patients or healthy controls. The percentages of IFN-gamma(+)TNF(+)CD8(+) T cells and IFN-gamma(+)CD4(+)T cells were determined by flow cytometry and cytokines released in the supernatant were detected by Cytometric Bead Array. Furthermore, PBMCs from patients with T. marneffei infection and healthy individuals were stimulated with IFN-gamma and anti-CD3/CD28 beads, and the levels of STAT1 and STAT3 phosphorylation were detected by Western blot. Results: The M1-reactive CD8(+)T cells that expressed IFN-gamma+TNF-alpha(+) of healthy controls were clearly reduced in serum with hightiter anti-IFN-gamma autoantibodies. In addition, the CD4(+)T cell response, designated by the expression of IFN-gamma, against T. marneffei in PBMCs of patients were significantly decreased when cultured in high-titer anti-IFN-gamma autoantibody serum culture, compared to the healthy compartments. Moreover, the release of the cytokines IFN-gamma, TNF-alpha and IL-2 was significantly decreased, while IL-10 was significantly increased. There was no significant difference in the phosphorylation levels of STAT1 and STAT3 protein between patients and healthy controls after IFN-gamma or anti-CD3/CD28 beads stimulation. Conclusion: Anti-IFN-gamma autoantibodies presence in the serum inhibited CD4(+) Th1 and CD8(+)T cell immune responses. There was no congenital dysfunction of STAT1 and STAT3 in anti-IFN-gamma autoantibody-positive patients with T. marneffei infection. These results suggest that the production of anti-IFN-gamma autoAbs impair T-lymphocyte responses.