Effects of Low-Dose Recombinant Interleukin 2 to Promote T-Regulatory Cells in Alopecia Areata

TLDR

An impaired inhibitory function of circulating CD4⁺CD25⁺ regulatory T cells has been implicated as a key factor in alopecia areata. The study reports the first use of low‑dose interleukin‑2 to treat severe alopecia areata by promoting Treg recruitment, evaluating its effect in a prospective open pilot study of five patients resistant to prior systemic therapies. Subcutaneous IL‑2 (1.5 million IU/d for 5 days, then 3 million IU/d in three 5‑day courses at weeks 3, 6, 9) was administered, with the primary outcome being change in Severity of Alopecia Tool score assessed by two investigators, and lesional skin biopsies and peripheral blood lymphocyte phenotyping performed. At six months, median SALT score fell from 82 to 69, Treg counts rose in 4 of 5 patients, no serious adverse events occurred, and partial regrowth in 4 of 5 patients supports the potential of Treg promotion for alopecia areata. Further studies are needed to confirm and optimize this approach, and the trial is registered at clinicaltrials.gov (NCT01840046).

Abstract

An impaired inhibitory function of circulating CD4+CD25+ regulatory T (Treg) cells was reported to play a key role in alopecia areata (AA). We report the first use to our knowledge of low-dose interleukin 2 for treating severe AA by promoting the recruitment of Treg cells.We conducted a prospective open pilot study in 5 patients with severe AA resistant to previous systemic treatments. Subcutaneous interleukin 2 (1.5 million IU/d) was administered during 5 days, followed by three 5-day courses of 3 million IU/d at weeks 3, 6, and 9. The primary outcome was the evolution of the Severity of Alopecia Tool (SALT) score, evaluated by 2 independent investigators on standardized photographs. Lesional skin biopsy specimens and peripheral blood lymphocyte phenotype were analyzed. The median SALT score went from 82 (range, 63-100) at baseline to 69 (range, 28-100) at 6 months. Immunochemical analysis revealed the appearance or a notable increase in Treg cell count in 4 of 5 patients at the end of the treatment compared with baseline. No serious adverse event was reported.The partial regrowth achieved in 4 of 5 patients and the recruitment of Treg cells in lesional skin support the interest of promoting Treg cells for treating AA. Further investigations are now required to confirm and to optimize the design in order to enhance the Treg cell response.clinicaltrials.gov Identifier: NCT01840046.