Treatment protocol:
Written informed consent was obtained from all parents and permission was taken from the health authority for off-label use. Patients received an initial loading dose of human plasma-derived AAT intravenously (IV) at 90 mg/kg followed by 60 mg/kg (P1, P3) and 30 mg/kg (P2) (depending on drug availability) IV every other day for 7 doses, total 8 doses.6 Serum AAT levels were measured at 24 and 48 hours after the infusion of AAT. Also, regulatory T cells (CD4+ CD25+FoxP3+ lymphocytes) were assessed by flow cytometry after the first, fourth and eighth doses.