The purpose of this study is to evaluate the safety and the dose-response relationship of ILT-101 to blood Tregs.

In the healthy physiological state, there is homeostasis between regulatory T cells (Tregs) and effector T cells (Teffs) which is deregulated in autoimmune diseases (AID).

The existence of an AID indicates a lack of Tregs. Our team has discovered that low-dose interleukin-2 (ld-IL2) activates and specifically increases Tregs in humans and thus may improve AID. Exploiting this potential requires i) to better target the dose with the best benefit / risk ratio and also ii) to better understand the mechanism of action of this molecule through clinical trials of ld-IL2 in progress, including in type 1 diabetes, multiple sclerosis and systemic lupus erythematosus. During these clinical trials, a very thorough immunological follow-up is carried out in order to discover biomarkers of treatment efficacy. Exploitation of these results will benefit both the cross-analysis of the effects of IL-2 in these 3 diseases with distinct pathophysiologies, but also very importantly a comparison with the effects of ld-IL2 at the healthy volunteer. These analyzes should make it possible to define the most effective dose of IL-2.

Inclusion Criteria:

• Without any chronic diseases diagnosed (including allergies);
• Effective contraception> 2 weeks before the first administration of the experimental drug or its placebo and β-hCG negative at the verification of the selection criteria;
• Affiliated to a social security system;
• Free, informed and written consent, signed by the subject and the investigator, before any action required by the research.
• Not taking any treatment

Exclusion Criteria:

• Subject in a period of exclusion of participation in other biomedical research;
• Participation in another research ≤ 1 month and during the study except for research Transimmunom (Non-interventional research involving the human person);
• known antecedents of autoimmune diseases;
• Hypersensitivity to any of the excipients of the investigational drug (mannitol, sodium laurilsulfate, monosodium phosphate dihydrate, disodium phosphate dihydrate);
• Evolutionary infection requiring treatment;
• Viral infection and benign infection less than 2 months old;
• Venous capital not allowing blood samples;
• Pregnant or lactating women;
• Men and women of childbearing potential without effective contraception during the study;
• Live attenuated virus vaccination in the month prior to inclusion or during the study;
• Surgical intervention ≤ 2 months or planned during the study;
• Psychiatric pathology or drug addiction that may impair ability to comply with protocol requirements or give informed consent;
• Presence or history of cancer that has not been cured for less than 5 years, except in situ cervical cancer, or basocellular cancer;
• Subject under a legal protection measure.