Nowadays, we generally think that the immune responses after the HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) of acute leukemia (AL) patients mainly results from the cross reactivate by donor-derived memory T-cells. However, the role of thymus on immune reconstitution after haplo-HSCT is not clearly understood yet.
Regarding the development of CD4-CD8− (double negative, DN) and CD4+CD8+ (double positive, DP) T-cell is associated with the function of thymus, we investigate the levels of DN and DP T-cell in AL patients who have received the haplo-HSCT or HLA-identical hematopoietic stem cell transplantation (identical-HSCT).
In the 1st to the 12th months after hematopoietic stem cell transplantation (HSCT), the DN T-cell and DP T-cell levels in the peripheral blood of 77 AL patients are evaluated by flow cytometry. And 51 of these patients received haplo-HSCT, while 26 of them received identical-HSCT. The repeated measures one-way ANOVA is used for statistic analysis.
The DP T-cell level of AL patients after haplo-HSCT is significantly higher than those patients after identical-HSCT (F = 12.02, p = 0.00). however, The DN T-cell level in these two groups of patients do not show a significantly difference (F = 0.87, p = 0.36). Furthermore, when we only look into the haplo-HSCT group, we found that the DP T-cell level of patients donated by the parents (n = 31) is significantly higher than that of the patients donated by the children, (n = 7, F = 6.37, p = 0.03) as well as that of the patients donated by the sister/brother(n = 13, F = 6.64, p = 0.02).
From the data of our center, in AL patients after haplo-HSCT show a high DP T-cell level than these patients after identical-HSCT, and this indicates that thymus as the human central immune organ, has a possibility to play a role in immune reconstitution after haplo-HSCT. But the clinical significance of DP T-cell on predicting thymus function and immune reconstitution need to be further explored with more patient data. Here, we would like to share our finding on the peripheral DP T-cell level after haplo-HSCT, in order to inspire further exploration with other hematologists to clarify the mechanism involve in it.