Correlation Between the Kinetics of CD3+ Chimerism and the Incidence of Graft-Versus-Host Disease in Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Introduction. Graft-versus-host disease (GvHD) remains a significant complication after allogeneic hematopoietic stem cell transplantation (HSCT). Early diagnosis and treatment may improve patient outcomes. A prospective study to investigate the relationship between chimerism kinetics and the development of acute or chronic GvHD was carried out. Split chimerism in association with the onset of GvHD was also analyzed. Methods. Thirty-three patients with hematologic diseases treated with allogeneic HSCT were analyzed. They were conditioned with myeloablative or reduced intensity regimens and grafted with peripheral blood (PB) or bone marrow stem cells. GvHD prophylaxis consisted of cyclosporine and methotrexate. Chimerism evaluation was performed on PB mononuclear cells and purified cell subsets consisting of separated CD3(+) T cells, monocytes (CD14(+)), and granulocytes (CD15(+)). Chimerism analysis was performed at 30, 60, 120, and a median of 200 days after HSCT. Results. Acute GvHD was diagnosed in 19 patients and chronic GvHD in 16. On day 30, no relation was found between the level of donor chimerism and aGvHD. Upon univariate analysis, decreasing mixed chimerism among CD3(+) and infused CD34(+) cell numbers was significantly correlated with acute GvHD development, while the PB stem cell source, reduced-intensity conditioning regimen, and female donor sex were associated with an increased risk of chronic GvHD. In multivariate analysis, the risk of acute GvHD correlated only with the CD34(+) cell dose, while the risk of extensive chronic GvHD was associated with high CD3(+) donor chimerism on day 30. Patients with versus without split chimerism (T cell vs myeloid lines) did not differ statistically in their incidence of acute GvHD or chronic GvHD. Conclusion. Our results supported the belief that chimerism kinetics or longitudinal chimerism evaluation is of greater significance than isolated absolute values of the percentage of chimerism at a single point after HSCT. The observations suggest that longitudinal monitoring of chimerism in CD3(+) T-cell subsets is an acceptable method to predict the development of GvHD among patients undergoing HSCT.