{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T08:47:11Z","timestamp":1785833231875,"version":"3.56.0"},"reference-count":40,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T00:00:00Z","timestamp":1785801600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000001","name":"Alberta Cancer Foundation","doi-asserted-by":"publisher","award":["27266"],"award-info":[{"award-number":["27266"]}],"id":[{"id":"10.13039\/501100000001","id-type":"DOI","asserted-by":"publisher"}]},{"award":["27266"],"award-info":[{"award-number":["27266"]}],"id":[{"id":"https:\/\/ror.org\/01k1b2g25","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cells"],"abstract":"<jats:p>Background: Cytomegalovirus (CMV) reactivation is a major complication after hematopoietic stem cell transplantation (HSCT). Natural killer (NK) cells help control CMV through killer-cell immunoglobulin-like receptors (KIRs) and their HLA ligands, but donor-derived CMV-specific T-cells may confound the interpretation of NK-mediated effects. Methods: We analyzed 276 HLA-matched (10\/10) adults receiving ATG-based T-cell-depleted myeloablative HSCT with a known donor and recipient CMV serostatus. The donor and recipient KIR genotypes were scored by the Cooley B-content score (0\u20134; \u22652 = high). Clinically significant CMV reactivation (plasma viral load &gt; 25,000 IU\/mL, the institutional threshold for pre-emptive therapy) was analyzed with Fine\u2013Gray competing-risks regression, stratified by the donor\u2013recipient serostatus. Results: In seronegative-donor\/seropositive-recipient (D\u2212R+) pairs (n = 68), a high donor KIR B-content score was associated with a significantly lower reactivation risk (sub-hazard ratio, 0.46; 95% CI, 0.24\u20130.91; p = 0.024). No effect was seen in D+R+ pairs (n = 82; SHR, 0.65; p = 0.241); D+R\u2212 (n = 28) had too few events to model. A donor Tel-AA\/recipient Tel-B+ mismatch was independently associated with a higher reactivation risk (adjusted HR, 2.41; 95% CI, 1.33\u20134.37; p = 0.004). The overall survival was unaffected in either stratum. Conclusions: A high donor KIR B-content score protects against CMV reactivation in D\u2212R+, but not D+R+, HSCT recipients, consistent with NK dominance when CMV-specific donor T-cells are sparse. A specific donor\u2013recipient telomeric mismatch independently modifies the risk. Donor KIR profiling warrants prospective evaluation in donor-selection algorithms.<\/jats:p>","DOI":"10.3390\/cells15151409","type":"journal-article","created":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T08:02:19Z","timestamp":1785830539000},"page":"1409","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Protective Role of Donor KIR B Haplotype in Cytomegalovirus Reactivation Following T-Cell-Depleted Hematopoietic Stem Cell Transplantation"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1319-6359","authenticated-orcid":false,"given":"Rehan M.","family":"Faridi","sequence":"first","affiliation":[{"name":"Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nazanin","family":"Vaziri","sequence":"additional","affiliation":[{"name":"Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohammad Saad","family":"Husain","sequence":"additional","affiliation":[{"name":"Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Poonam","family":"Dharmani-Khan","sequence":"additional","affiliation":[{"name":"Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada"},{"name":"Alberta Precision Labs, Calgary, AB T2N 5G2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amit","family":"Kalra","sequence":"additional","affiliation":[{"name":"Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Noureddine","family":"Berka","sequence":"additional","affiliation":[{"name":"Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada"},{"name":"Alberta Precision Labs, Calgary, AB T2N 5G2, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jan","family":"Storek","sequence":"additional","affiliation":[{"name":"Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada"},{"name":"Alberta Health Services, Calgary, AB T2N 4N1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Faisal M.","family":"Khan","sequence":"additional","affiliation":[{"name":"Cumming School of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada"},{"name":"Alberta Precision Labs, Calgary, AB T2N 5G2, Canada"},{"name":"Alberta Health Services, Calgary, AB T2N 4N1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Alyazidi, R., Murthy, S., Slyker, J.A., and Gantt, S. 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