Increased viral load after intravenous immunoglobulin therapy for BK virus-associated nephropathy

Intravenous immunoglobulins (IVIG) have been proposed as a treatment for BK virus-associated nephropathy (BKVAN), based on their alleged anti-in£ammatory and BKVneutralizing activities (1).While it appears reasonable to exploit their anti-in£ammatory activity for treating BKVAN with a marked in£ammatory component, with or without coexisting rejection (2), the BKV neutralizing e¡ect of IVIG appears questionable, as recent studies have shown that BKV active replication occurs despite markedly high levels of BKV-speci¢c immunoglobulin G (IgG) (3^5). The evidence in favor of the use of IVIG comes fromthe initial experience with 8 cases of BKVAN and from other subsequent reports (1, 6). However, in none of these studies was the viral load monitored by quantitative polymerase chain reaction (PCR) assay immediatelyafter IVIG therapy, and therefore no direct evidence was provided to determine the e¡ect of IVIG on viral clearance. In this letter we describe a patient su¡ering from BKVAN whomwe treated with tapering of immunosuppression and with IVIG. In this patient, we performed serial measurements of plasma BKviral load before and after IVIG administration.