BK virus–specific T-cell reconstitution patterns in cases and controls. (A) Time to first detection of BK virus–specific IFN-γ⁺, IL-2⁺, TNF-α⁺, and cytolytic CD8 and CD4 T cells in BK virus-positive cases and BK virus-negative controls. Differences between curves were assessed by the log-rank test. (B) Absolute individual patient IFN-γ⁺, IL-2⁺, TNF-α⁺, and cytolytic CD8 and CD4 T-cell counts over time, in patients with detectable cells at any time point.