Graft-versus-host disease (GVHD) is a primary cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation (allo-HSCT). The inflammatory state during immune reconstitution is critical, with neutrophils, lymphocytes and platelets playing relevant roles in the cascade of thromboinflammatory events that underlie the pathogenesis of post HSCT complications. Yet the prognostic value of simple biomarkers reflecting the balance between these cells such as the neutrophil-to-platelet ratio (NPR) and neutrophil-to-lymphocyte ratio (NLR) requires further clarification for different post-transplant complications.

This study aimed to investigate the association between NPR and NLR, measured at admission and at neutrophil engraftment, with the development of acute GVHD (aGVHD), chronic GVHD (cGVHD), and overall survival (OS) in patients undergoing allo-HSCT.

We conducted a retrospective, single-center study including 173 adult patients who underwent their first allo-HSCT between January 2012 and December 2021. NPR and NLR were calculated at admission and on the day of neutrophil engraftment. Baseline variables recognized as potential predictors of negative outcomes after allo-HSCT were prospectively registered as part of patient management and obtained from the medical records.

The patient cohort (n = 173) had a median age of 44 years (IQR: 32-55) and included 58.4% males. Overall survival was 63.4% after a median follow-up of 194 days (IQR 50-917). The predominant graft source was peripheral blood stem cells (86.13%), and fully HLA-matched donors accounted for 78.61% of cases. The cumulative incidence of grade II-IV acute GVHD (aGVHD) was 16.8%, and chronic GVHD (cGVHD) occurred in 24.9% of patients. In a multivariate analysis, OS was independently associated with platelet count at admission (p = 0.037) and NPR at engraftment (p = 0.005). cGVHD was associated with HLA match (p = 0.013), platelet count at admission (p = 0.031) and female donor to male receptor (p = 0.030). Finally, grades 2-4 aGVHD were independently associated with NLR at admission (p = 0.04) and female donor to male receptor (p = 0.005).

Activation of innate immunity is a critical element in the cascade of events that influence acute and chronic complications of allo-HSCT, that can also influence survival. NPR and NLR can be regarded as proxies of the activation of these immune compartments so that our findings add insights about the pathogenesis of these complications. In addition, if validated in independent and larger cohorts, these ratios may represent inexpensive and readily available biomarkers that can contribute to the risk stratification of these patients.