CD8A and post-transplant lymphoproliferative disease: Other factors associated with PTLD include: (1) CD8+ count (≥median vs. <median) 30 days after HSCT (HR = 0.34 (0.13–0.92)), (2) prior HSCT ((HR = 2.6 (1.1–6.4)) [57], (RR = 3.5 [1.7–6.3)) [70]), (3) splenectomy (SHR = 4.81 (1.51–15.4)) [94], (4) infusion of mesenchymal stromal cells (SHR = 3.05 (1.25–7.48)) [94], (5) a stepwise increase of EBV-DNA by 1 log (HR = 2.9 (1.7–4.8)) [96], (6) HLA DRB1*11:01 (SHR = 4.85 (1.57–14.97)) [82], and (7) HLA mismatch (SHR = 5.89 (2.43–14.3)) [94].