To analyze the reconstitution of lymphocyte subset at various time points before and after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children with severe β-thalassemia.

Twenty-two children with severe β-thalassemia who completed allo-HSCT from December 2021 to August 2023 in Maoming People′s Hospital were selected as the study objects. The changesof lymphocyte subsets, including CD3⁺ T cell ratio, CD4⁺ T cell ratio, CD8⁺ T cell ratio, CD19⁺ B cell ratio, NK cell ratio and CD4⁺ /CD8⁺ ratio, were dynamically monitored before and 10, 30 and 60 days after allo-HSCT in all children. To compare the changes of lymphocyte subsets at each time point between HLA complete and incomplete match children and children of different genders. On the day of donor peripheral blood stem cell reinfusion, lymphocyte subsets of related donors were also measured to analyze the correlation between donor immunity and the occurrence of postoperative acute graft-versus-host disease (aGVHD) in children. Measurement data were expressed as mean±standard deviation (±s) and compared using group t-test or repeated measures analysis of variance; enumeration data were expressed as frequency and compared using Fisher′s exact test. P<0.05 was considered statistically significant.

The success rate of allo-HSCT was 100% in 22 cases, all of which were separated from blood transfusion, including 15 cases of HLA complete match and 7 cases of HLA incomplete matched. There was no significant difference in gender composition, age and three-lineage implantation time between the two groups. The proportion of NK cells exceeded the preoperative level at 10 d and 30 d after allo-HSCT (P<0.05), and decreased to the preoperative level at 60 d after allo-HSCT (P>0.05). The proportion of CD19⁺ B cells decreased transiently at 30 d after operation and rose to a higher level than 30 d at 60 d after allo-HSCT, but it was still lower than the preoperative level (all P<0.05). The proportion of CD3⁺ T cells and CD8⁺ T cells showed a transient decrease at 10 d after allo-HSCT (all P<0.05), and recovered to the preoperative level at 30 d and 60 d after allo-HSCT (all P>0.05). The proportion of CD4⁺ T cells was lower than the preoperative level at all time points after allo-HSCT, but there was no significant difference between 60 d after allo-HSCT and preoperative level (P>0.05). The CD4⁺ /CD8⁺ ratio at each time point after surgery was lower than the preoperative level, but the differences were not statistically significant (P>0.05). There was no statistically significant difference in the changes of lymphocyte subsets between HLA complete and incomplete match children as well as children of different genders at each time points before and after allo-HSCT (P>0.05). There was no significant association in the proportion of lymphocyte subsets between related donors of children who developed and those who did not develop aGVHD (P>0.05).

Lymphocyte subsets fluctuate after allo-HSCT in children with β-thalassemia major, and there is no difference in lymphocyte subsets between HLA complete and incomplete match and between genders; the level of lymphocyte subsets in related donors is not associated with aGVHD in children.