The purpose of the study is to evaluate the safety and type 1 Interferon (IFN) neutralization in patients with refractory severe Hidradenitis Suppurativa (Hurley stage III) after transfusion of plasma containing high titer anti-IFN-1 autoantibodies.

Inclusion Criteria:

• Men and women aged over 18
• Patients with Hidradenitis suppurativa (Hurley stages II-III)
• Disease affecting at least two distinct anatomical areas,
• Total count of abscesses (A) and inflammatory nodules (N) ≥ 3
• IHS4 score ≥ 11
• Treatment of pain with opioids (≥ 20 mg/day)
• Resistance to previous use (for at least 3 months) of systemic antibiotics and TNF inhibitors (infliximab or adalimumab) or anti-IL17 (secukinumab).
• Vaccinations against SARS-CoV-2 and influenza up to date (or able to be carried out prior to the study procedure)
• Women using an effective method of contraception
• Signed informed consent

Exclusion Criteria:

• Active viral infection: herpes, VZV, HIV, HBV, HCV
• Active bacterial infection requiring systemic antibiotics
• Known allergy to blood components/plasma proteins
• Poor myocardial function (increased risk of for transfusion-associated circulatory overload) (symptomatic left ventricular failure and ejection fraction < 40%)
• Pregnant women
• Subjects with no social security coverage