Regulatory functions of normal IgG and regulatory T cells in physiopathology.

We investigate the role of IgG and regulatory T cells in immune homeostasis, immunotherapy of inflammatory diseases and vaccine response.

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Normal IgG in the body have various immunoregulatory functions. Many of these functions are deciphered through the therapeutic use of intravenous immunoglobulin or IVIG, a pooled normal IgG from several thousand healthy donors. IVIG is extensively used in the immunotherapy of diverse autoimmune and inflammatory pathologies. Our aim is to identify the molecular targets and pathways through which IVIG inhibits (inflammation and autoimmunity while enhancing immune tolerance. We thus hope to unravel novel molecular mechanisms of IVIG and to identify biomarkers to predict patient responsiveness to treatment.
Regulatory T cells (Tregs) are indispensable for immune tolerance. Mechanistically, Tregs suppress the activation of diverse immune cells.. However, contrary to the dogma that Tregs are “universal immunosuppressive cells”, we have recently demonstrated that Tregs induce activation of human basophils by a mechanism dependent on IL-3 and STAT5. We are currently investigating the various facets of the cross-talk between these two rare immune cells and the therapeutic strategies that target basophils in inflammatory conditions. Additionally, we are exploring the role of Tregs in regulating the protective immune response to pathogens (including SARS-CoV-2) and vaccines (flu).