The presence of IFNG 3/3 genotype in the recipient associates with increased risk for Epstein–Barr virus reactivation after allogeneic haematopoietic stem cell transplantation

Recent studies have shown that interferon-γ gene (IFNG) polymorphism constitutes a risk factor for acute and chronic graft-versus-host disease (GvHD) after allogeneic haematopoietic stem cell transplantation (HSCT). Patients with IFNG 3/3 have been found to be more prone to GvHD. This rather puzzling result, as 3/3 genotype is associated with a decreased IFN-γ production, was investigated in the present study in the context of Epstein–Barr virus (EBV) reactivation. Microsatellite polymorphism (CA)_n within the first intron of IFNG gene was assessed in 83 HSCT recipients and related to EBV load. Quantification of EBV copies was performed by a real-time polymerase chain reaction in peripheral blood cells taken from the patients 2–3 months after HSCT. It was found, that patients having IFNG 3/3 genotype presented with a high number of EBV copies (over 10/10⁵ blood cells) when compared with the recipients with other IFNG genotypes (10/14 vs. 17/69, P < 0·001). This association was independent of recipient's age, underlying disease, conditioning regimen, type of donor, source of stem cells or pretransplant donor and recipient EBV serological status. Thus IFNG 3/3 genotype, known to be associated with a decreased IFN-γ production, appeared as a factor significantly contributing to the risk of EBV reactivation after allogeneic HSCT.