Human CMV infection is the most common opportunistic infection after kidney transplantation, with a negative impact on kidney allograft outcome. Transplant recipients are at higher risk of CMV infection because of immunosuppression, particularly when using T-cell depleting agents such as rabbit anti-thymocyte globulin (rATG). CMV-specific T and B-cell responses are crucial for controlling viral replication. Whether CMV-specific memory T and B cells repopulate after rATG treatment and how they influence on CMV infection has not been well documented yet.

Methods: We evaluated CMV-specific memory T and B cell responses using the IFN-Y and IgG ELISPOT assays. 70 consecutive kidney transplant patients receiving either rATG (n=42) or anti-IL2R monoclonal antibodies (basiliximab®) (n=28) followed by tacrolimus, MMF and steroids. We monitored the kinetics of T and B-cell responses against two dominant CMV antigens (IE-1 and pp65) at baseline, two weeks and at one, three and six months after transplantation and evaluated their impact on CMV infection.

Results: rATG-treated patients showed a generalized abrogation of CMV-sp T-cell frequencies over the first 6 months as compared to basiliximab-treated patients that also showed reduced CMV-sp T-cell frequencies over time. RATG-treated patients showed lower CMV-sp T-cell frequencies at 2 weeks(p<0.05) but fully recovered by months 3 and 6 for pp65 and IE-1, respectively as compared to baseline (P=NS). No impact on CMV-sp T-cell responses was observed regarding the type of preventive strategy used. Notably, patients not recovering sufficient CMV-sp T-cell frequencies more likely developed CMV infection after kidney transplantation. CMV-sp memory B-cell frequencies were not influenced by the use of T-cell depletion nor basiliximab®.

Conclusions: rATG induction significantly impacts on early CMV-sp memory T-cell responses after transplantation, although a rapid CMV-sp T-cell homeostatic proliferation might be observed in some patients thus, driving protection against CMV infection.

CITATION INFORMATION: Jarque M, Luque S, Crespo E, Melilli E, Torras J, Grinyó J, Bestard O. Impact of T-Cell Depletion on CMV-Specific Memory T and B Cell Homeostatic Proliferation After Kidney Transplantation. Am J Transplant. 2017;17 (suppl 3).

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