MuTreg

Treatment tested

• Blood sample taken at a single time point

Inclusion Criteria: * Inclusion criteria common to all patients in different departments: * Age18 years * Affiliated to social security or entitled to * Patient who has been informed of the study and has signed a free and informed consent Inclusion criteria specific by department: Inclusion criteria for Clinical Hematology Department: * Patient with GVHD following allogeneic hematopoietic stem cell transplantation (HSC) * Or with acquired bone marrow suppression * Lymphocytosis > 0.5 G/L Inclusion criteria for Nephrology and Transplantation department: - Patient with systemic lupus erythematosus (ACR classification criteria) Inclusion criteria for Neurology department: - Patient with multiple sclerosis (criteria of Mc Donald 2017) Inclusion criteria for Rheumatology Department: - Patient with rheumatoid arthritis (ACR classification criteria) Inclusion criteria for Internal Medicine-Endocrinology Department: - Patient with Basedow disease, Hashimoto's thyroiditis Inclusion criteria for Dermatology Department: - Patient with vitiligo or alopecia areata or atopic dermatitis Exclusion Criteria: Non-inclusion criteria common to all patients: * Patient under guardianship, curatorship or judicial protection * Pregnant, parturient or breastfeeding woman * Patient deprived of liberty * Patient hospitalized without consent * Patient admitted to a health or social institution for purposes other than research * Minor patient * Adult patient unable to express consent * Refusal to participate * Patient on AME Non-inclusion criteria specific by department: Non-inclusion criteria for Clinical Hematology Department: * Ongoing treatment with high doses (>1 mg/kg/d) of systemic corticosteroid therapy * Ongoing treatment with JAK inhibitors Non-inclusion criteria for Nephrology and Transplantation Department: * Ongoing treatment with doses >10 mg/d Prednisone * Ongoing treatment with Cellcept, Endoxan, Imurel, Belimumab, Anti-CD20, Methotrexate * Ongoing treatment with JAK inhibitors Non-inclusion criteria for Neurology Department: * Treatment with systemic corticosteroid therapy, Fingolimod or Teriflunomide * Ongoing treatment with JAK inhibitors * Lymphocytosis \< 0.5 G/L Non-inclusion criteria for Rheumatology Department: * Ongoing treatment with doses >15 mg/d Prednisone * Treatment with Rituximab or Tocilizumab * Ongoing treatment with JAK inhibitors * Lymphocytosis \< 0.5 G/L Non-inclusion criteria for Internal Medicine - Endocrinology Department: * Ongoing immunosuppressive therapy * Ongoing treatment with JAK inhibitors Non-inclusion criteria for Dermatology Department: * Ongoing treatment with Methotrexate * Ongoing treatment with JAK inhibitors * Ongoing treatment with doses >10 mg/d prednisone

Interleukin 2 (IL-2) is a critical cytokine for the survival and function of regulatory T cells (LTreg). This cytokine has a dual role in the immune system. IL-2 stimulates immune responses by acting on the intermediate affinity IL-2R receptor, IL-2Rβγ, expressed by conventional T cells (LTconv) during activation, but also contributes to the inhibition of immune responses via LTreg that express the high affinity receptor IL-2Rαβγ. This difference in IL-2 receptor affinity for IL-2 has led to the development of low-dose IL-2 therapy to stimulate LTreg and improve control of excessive inflammation in autoimmune (AID), inflammatory or alloimmune diseases Low-dose IL-2 therapy is being studied in several of these diseases such as systemic lupus erythematosus, type 1 diabetes, alopecia, HCV (hepatitis C virus)-induced vasculitis, atopic dermatitis and chronic allo-transplantation-related graft-versus-host disease (GVHD). Some of these studies have shown an increase in LTreg numbers and an improvement in certain clinical signs. To improve LTreg targeting in autoimmune diseases, inflammatory diseases or GVHD, mutated IL-2s (muteins) have been developed with selective LTreg agonist properties. These IL-2 muteins are linked to an Fc fragment to increase their half-life. Two IL-2 variants (IL-2Vs)-Fc preferentially stimulate STAT5 phosphorylation in LTregs compared to conventional FoxP3- (LTconv) CD4+ or CD8+ T cells