CD4 and lymphopenia: Although we were unable to analyze CD4 + /CD8 + cell count due to too many missing data, our findings are in line with those of Schachtner et al. who showed that a loss of detectable BKV-specific T-cells as well as absolute lymphopenia (measured by CD3 + , CD4 + and CD8 + T cell counts) were highly predictive risk factors for BKV infection [36].