*Purpose: The transplantation field needs biomarkers to assess the level of immunosuppression. In this study, we aimed to analyze the independent correlation between the number of circulating lymphocytes, simply and routinely monitored by complete blood count during outpatients visits, and patient and graft survival to explore its potential role as a biomarker of immunosuppression.

*Methods: 3002 kidney or combined kidney-pancreas transplanted patients between January 2000 and December 2016, from two french University Hospitals, alive with a functioning graft at 1 year post-transplantation, were enrolled in the study. Their data were extracted from the DIVAT data base. We investigated the etiological relationship between time-dependent lymphocyte count after one year of transplantation and patient and graft survival and viral infections, using a Cox multivariate model analysis.

*Results: we showed that patients with at least one lymphocyte count below 750 /mm3 within the follow-up had a higher risk of graft failure (HR 3.08, p<0.001) and death (HR 2.06, p<0.001) when compared to patients with a normal lymphocyte count (more than 1500 /mm3), independently from other classical confounding factors. Patients with less than 750 /mm3 lymphocytes were more at risk of viral infections than patients with a normal lymphocyte count (HR 1.62, p<0.001).

*Conclusions: deep lymphopenia over time is highly associated with a risk of graft failure, death and viral infection occurrence. These data suggest that the longitudinal lymphocyte count could be used as a simple routine biomarker of long-term graft and patient outcome.

« Back to 2019 American Transplant Congress