Naive Donor NK Cell Repertoires Associated with Less Leukemia Relapse after Allogeneic Hematopoietic Stem Cell Transplantation

• Acute and latent human CMV cause profound changes in the NK cell repertoire, with expansion and differentiation of educated NK cells expressing self-specific inhibitory killer cell Ig-like receptors. In this study, we addressed whether such CMV-induced imprints on the donor NK cell repertoire influenced the outcome of allogeneic stem cell transplantation. Hierarchical clustering of high-resolution immunophenotyping data covering key NK cell parameters, including frequencies of CD56bright, NKG2A+, NKG2C+, and CD57+ NK cell subsets, as well as the size of the educated NK cell subset, was linked to clinical outcomes. Clusters defining naive (NKG2A+CD57−NKG2C−) NK cell repertoires in the donor were associated with decreased risk for relapse in recipients with acute myeloid leukemia and myelodysplastic syndrome (hazard ratio [HR], 0.09; 95% confidence interval [CI]: 0.03–0.27; p < 0.001). Furthermore, recipients with naive repertoires at 9–12 mo after hematopoietic stem cell transplantation had increased disease-free survival (HR, 7.2; 95% CI: 1.6–33; p = 0.01) and increased overall survival (HR, 9.3; 95% CI: 1.1–77, p = 0.04). Conversely, patients with a relative increase in differentiated NK cells at 9–12 mo displayed a higher rate of late relapses (HR, 8.41; 95% CI: 6.7–11; p = 0.02), reduced disease-free survival (HR, 0.12; 95% CI: 0.12–0.74; p = 0.02), and reduced overall survival (HR, 0.07; 95% CI: 0.01–0.69; p = 0.02). Thus, our data suggest that naive donor NK cell repertoires are associated with protection against leukemia relapse after allogeneic HSCT.

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