Precision in donor selection: Identifying ideal stem-cell donors through their T cells

Area of Science:

• Hematology
• Immunology
• Transplantation Science

Background:

• HLA-identical siblings are traditionally considered optimal donors for allogeneic hematopoietic stem-cell transplantation (allo-HSCT).
• Recent findings challenge this paradigm, suggesting donor T-cell composition is critical.

Purpose of the Study:

• To investigate the impact of graft T-cell composition on outcomes in allo-HSCT with reduced-intensity conditioning (RIC).
• To identify specific donor characteristics associated with improved patient survival and reduced disease relapse.

Main Methods:

• Analysis of outcomes in 200 patients with hematologic malignancies undergoing allo-HSCT with RIC.
• Focus on T-cell content, specifically CD8+ T-cell dose, in peripheral blood stem-cell grafts.
• Correlation of graft composition with patient survival, relapse risk, and graft-versus-host disease (GVHD).

Main Results:

• Higher graft CD8+ T-cell dose (CD8hi), prevalent in younger donors, significantly improved survival by reducing relapse risk.
• A low CD4:CD8 ratio in peripheral blood identified donors with CD8hi grafts.
• Donor age inversely correlated with the likelihood of finding CD8hi grafts, impacting elderly recipients.

Conclusions:

• Graft CD8+ T-cell dose is a crucial factor in allo-HSCT outcomes, potentially refining donor selection criteria.
• Donor age and peripheral blood CD4:CD8 ratio are important considerations for identifying optimal donors.
• Rethinking donor selection based on T-cell composition may enhance allo-HSCT efficacy for hematologic cancers.