Bacchetta J et al. - Due to the presence of macroscopic haematuria and proteinuria, a renal biopsy was performed and showed acute proliferative relapse of IgAN. The underlying mechanism of inulin hypersensitivity is not well known. We can hypothesize that inulin had activated the innate immune system. Inulin may, thus, have been the initiating event of the renal relapse, acting like an infection, in a patient with IgA-mediated immunological dysregulation.