Nephrotic-range proteinuria on interferon-β treatment: immune-induced glomerulonephritis or other pathway?

We present a case report of a 37-year-old woman with multiple sclerosis (MS) who developed nephrotic-range proteinuria secondary to membrano proliferative glomerulonephritis (MPGN)-like disease with mesangial C3 deposition without evidence of immune-complex deposition in the context of long-term interferon-β (IFN-β) therapy. The complete remission of proteinuria following cessation of IFN-β, strongly suggests causality. To our knowledge, this is the second case report of MPGN associated with IFN-β use. This being the case, the negative immune screen, normal inflammatory markers and the absence of immune complex deposits would imply a different pathway to that previously suggested.