Gerardo Botti

Prospective monitoring of polyomavirus BK replication and impact of pre-emptive intervention in pediatric kidney recipients.

Polyoma BK virus (BKV)‐associated nephropathy (PVAN) is a relevant cause of poor renal allograft survival. In a prospective analysis, we monitored BKV DNA in blood and urine samples from 62 consecutive pediatric kidney recipients. In patients with BKV replication, we analyzed the impact of reduction of maintenance immunosuppression on viral load kinetics and PVAN in patients with BKV replication. BKV‐specific immunity was concomitantly evaluated on blood samples of viremic patients, by measuring the frequency of BKV‐specific interferon‐γ‐producing and cytotoxic T cells, and BKV IgG antibody levels. At a median follow‐up of 24 months, BK viruria was observed in 39 of 62 patients, while BK viremia developed in 13 patients (21%). In all viremic patients, immunosuppression reduction resulted in the clearance of viremia, and prevented development of PVAN, without increasing the rate of acute rejection or causing graft dysfunction. As a consequence of immunosuppression adjustment, an expansion of BKV‐specific cellular immunity was observed that coincided with viral clearance. We conclude that treating pediatric kidney transplant patients pre‐emptively with immunosuppression reduction guided by BKV DNA in blood is safe and effective to prevent onset of PVAN. BKV‐specific cellular immunity may be useful to guide this intervention.

Treatment of EBV-Related Post-Renal Transplant Lymphoproliferative Disease with a Tailored Regimen Including EBV-Specific T Cells

The treatment of EBV‐associated post‐transplant lymphoproliferative disease (PTLD) poses a considerable challenge. Efforts have been made to define regimens based on combination of the available therapeutic agents, chosen and tailored on a patient‐by‐patient basis, with the aim of augmenting event‐free patient and graft survival. Recently, autologous EBV‐specific cytotoxic T‐lymphocytes (CTL) have proved effective in enhancing EBV‐specific immune responses and reducing viral load in organ transplant recipients with active infection. We investigated the use of a tailored combined approach including autologous EBV‐specific CTL for the treatment of EBV‐related PTLD developing after pediatric kidney transplantation.

Polyomavirus BK-specific immunity after kidney transplantation.

Failure to mount or maintain a protective immune response may influence the development of polyomavirus BK (BKV)-associated nephropathy (PVAN). However, limited data are so far available on BKV-specific immunity after kidney transplantation. BKV-specific cellular immune response was retrospectively analyzed in kidney recipients with or without BKV infection/reactivation by measuring the frequency of interferon (IFN)-gamma-secreting cells in peripheral blood. Patients with BKV-active infection and good renal function (n=6) had a mean BKV-specific lymphocyte frequency 2 log lower than healthy controls and in the same range as BKV-seropositive recipients without active infection (n=7). Patients with PVAN (n=5) revealed undetectable levels of BKV-specific cells. However, two patients from the latter cohort treated with immunosuppression reduction showed the emergence of specific immunity, with IFN-gamma production in the same range as healthy controls. Our preliminary data suggest that lack of protective immunity toward BKV may favor the occurrence of BKV active infection and influence the progression to PVAN.