A retrospective analysis of autoimmune hemolytic anemia after allogeneic hematopoietic stem cell transplantation for transfusion-dependent β-thalassemia: focus on T and B lymphocyte reconstitution

Background: Autoimmune hemolytic anemia (AIHA) following allogeneic hematopoietic stem cell transplantation (allo-HSCT) is often refractory and relapsing, leading to increased mortality post-HSCT.

Methods: We retrospectively analyzed the cases of patients with transfusion-dependent β-thalassemia (TDT) who underwent allo-HSCT to study their clinical features, the occurrence of AIHA post-HSCT, and treatment response and to explore the possible pathogenesis of AIHA.

Result: A total of 113 patients were registered in the study, out of whom 14 developed AIHA following allo-HSCT, resulting in a cumulative incidence of 12.4%. The median age at HSCT was 5 (range: 2-14) years, and the median time of occurrence was 8 (range: 4-17) months after HSCT. Patients who are less than 4 years old at the time of HSCT (P = 0.032) exhibit a higher incidence of AIHA. Compared to patients without AIHA, AIHA patients demonstrate a lower percentage of B lymphocytes at the first 100 days (day + 100) post-HSCT(P = 0.002). There were no statistically significant differences in gender, unrelated donors, HLA incomplete mismatch, iron overload, ABO incompatibility, cytomegalovirus (CMV) reactivation, Epstein Barr virus (EBV) reactivation, acute and chronic graft-versus-host disease (GvHD). When AIHA occurred, the absolute value of regulatory T cells decreased without a clear reduction in the proportion of CD4 + cells, and there was no significant elevation of interleukin-17. Eventually, 78.6% (11/14) of patients achieved complete remission with corticosteroids and rituximab, and patients who failed were efficacious with the bortezomib in combination with corticosteroids. Four patients experienced relapse, with one of them relapsing twice. Two patients relapsed after bortezomib and subsequently achieved remission with retreatment using a combination of corticosteroids and rituximab. All AIHA patients were alive and without relapse at the follow-up cutoff.

Conclusions: Patients suffering from TDT are more prone to developing AIHA following allo-HSCT, potentially due to a disruption in the reconstitution balance of T and B lymphocytes. Despite the high incidence, the response to treatment was excellent. For relapsed/refractory patients, alternate therapy with bortezomib and rituximab may be considered.