Immunological Evaluation after Haematopoietic Stem Cell Transplantation for B–Thalassemia Major

Background: Haematopoietic stem cell transplantation (HSCT) remains the only curative option for patients with thalassemia. After HSCT is particularly important to recover a complete immune reconstitution for prevention of opportunistic infections.

Methods: The immunological phenotype of peripheral blood mononuclear cells in 110 consecutively subjects after HLA identical HSCT performed for b thalassemia were studied. CD3+CD4+, CD3+CD8+, CD3−CD19+, CD3−CD16+CD56+ were evaluated by Flow Cytometry at 6 and 12 months after HSCT in 70 patients followed. In a part of patients CD4 naïve T cells was also evaluated at 12 months after HSCT.

Results: at 6 months after HSCT we observed reduction of the mean of CD4 T cell percentage in patients respect normal value: in mean 17, 5 % ± 9 vs 45 % ± 10 respectively. After 1 year the rate of CD4+ T-cell population progressively increase: 24 ± 9 at 12 months vs 17, 5 % ± 9 at 6 months, but the mean of CD4+ T-cell count was persistently lower than in controls. The mean of CD8 T cell is stable during the follow up and the CD4/C8 ratio decreased. The mean of the CD19 increase during the follow up (4, 5 % at 6 months vs 17% at 12 months). At 1 year after HSCT the percentage of NK (CD3−CD16+CD56+) was normalized. At 1 year after HSCT reduction of naïve CD4 T cell we observed.

Discussion. At 1 year after HSCT the immunological reconstitution is not still complete. The time and the extent of immune reconstitution depend on several factors. It is very important to continue the immune surveillance after HSTC and to evaluate other immunological parameters (i.e. thymic output) for to prevent infectious complications and elaborate an appropriate therapeutic strategy.