Gamma Delta T Cells: A Prospective Analysis of Their Regeneration Kinetics and Their Impact on the Clinical Outcome Following Allogeneic Hematopoietic Stem Cell Transplantation

Haematopoietic stem cell transplantation (HSCT) plays an important role in the therapy of hematological malignancies. Gamma delta T cells (ᵞᵟ T cells) are a distinct lineage of T lymphocytes that might play an important role in immune recovery and could utilize a graft –versus –leukemia effect post HSCT, furthermore, higher counts of ᵞᵟ T cells could improve clinical outcome after HSCT. This work was conducted to analyze the kinetics of gamma delta T cells recovery post HSCT, and to correlate their reconstitution with different factors that may influence the clinical outcome following HSCT. In this study, 22 consecutive allogeneic hematopoietic stem cell transplantation (HSCT) recipients were analysed during the first-year post transplantation by measuring the absolute count of CD3 T cells and percentages of gamma delta T cells subsets every month for each patient using flow cytometric technique. Statistics (means, minimal, and maximal values) were used to describe patient baseline characteristics. Results were presented as mean values of CD3+, gamma delta T cells %, and p-values. Higher gamma delta T cells percentages were significantly correlated with younger patient and donor age, sex matched transplantation, leukemic diseases, un-manipulated transplants, and in patients without chronic graft versus host disease complications. Furthermore, positive correlation between CD3 T cells counts and gamma delta T cells % was also determined. Overall survival and better clinical outcome following allogeneic HSCT could be related with proper gamma delta T cells reconstitution.