Integration of peripheral blood lymphocyte count kinetics and bone marrow hematogones for stratifying B-cell recovery and clinical outcomes after cord blood transplantation: a retrospective study.

Immune reconstitution after allogeneic hematopoietic stem cell transplantation influences clinical outcomes. However, the optimal clinical laboratory evaluation parameters remain unclarified. This retrospective study analyzed first-time cord blood transplant (CBT; without anti-thymocyte globulin) recipients (n = 837; cohort) and unrelated bone marrow (BM) transplant recipients (n = 122; controls). A novel lymphocyte reconstitution (LR) classification, integrating peripheral blood lymphocyte count kinetics on post-CBT days 20, 30, and 50, and hematogones in the BM test confirming neutrophil engraftment, emerged as a valuable evaluator of B lymphocyte recovery in the 1-year post-CBT period. The LR classification further helped stratify progression-free survival and cumulative non-relapse mortality incidence. Multivariate logistic regression analyses identified splenomegaly as a significant risk factor in LR-favorable vs. intermediate (hazard ratio, 2.21; p = 0.04) and LR-favorable vs. adverse (hazard ratio, 2.89; p = 0.01). The LR classification may have clinical utility as a prognostic evaluator during the early post-CBT period.