Immunoglobulin therapy may be effective in treating severe IgA nephropathy and protecting renal function. However, prospective controlled trials must confirm these preliminary results.

Recently, our group has shown that a 3-month course of intravenous immunoglobulin (2 g/kg/monthly) followed by 6 months of intramuscular immunoglobulins (IMIG, 16.5%, 0.35 ml/kg every 15 days) was able to slow or to stop the decline in the glomerular filtration rate, to reduce proteinuria, hematuria, leukocyturia and the histological index of activity on renal biopsy in patients with severe forms of IgA nephropathy (IGAN) and Henoch-Schönlein purpura (HSP). The aim of this open prospective trial was to evaluate the efficacy and safety of low-dose immunoglobulin therapy in moderate IGAN and HSP with permanent proteinuria. Fourteen patients with moderate IGAN [idiopathic IGAN: n= 11; chronic idiopathic HSP: n = 3] and permanent albuminuria were treated with polyvalent IMIG (16.5%) for 9 months (0.35 ml/kg once a week for 1 month, followed by 0.35 ml/kg every 15 days for a further 8 months). Eligibility criteria in the study were Lee histological stage I, II or III, albuminuria between 300 and 2,000 mg/ day and a glomerular filtration rate > 70 ml/min/1.73 m². IMIG were well tolerated and only 1 patient withdrew from the trial. No viral, renal or immunological side effects were observed. IMIG induced a significant decrease in albuminuria as well as in the histological activity index in the 11 cases in which a follow-up biopsy was performed. There was also a decrease in serum IgA, serum β₂-microglobulin and IgA immune complex levels, and an increase in serum IgG₁ levels. Twelve of the 13 evaluable patients improved during treatment. Systemic symptoms disappeared after 2 months of starting IMIG in the 3 HSP patients. IMIG therapy for IGAN only appeared to be suspensive, since its withdrawal was followed by relapse. We conclude that IMIG may be an effective immunomodulatory treatment of IGAN and HSP, although prospective controlled trials are required to confirm these preliminary results.