Analysis of immune reconstitution after autologous CD34 ⁺ stem/progenitor cell transplantation for systemic sclerosis: Predominant reconstitution of Th1 CD4 ⁺ t cells

Objective: The aim of this study is to evaluate the mechanism of long-term effect of autologous haematopoietic stem cell transplantation (ASCT) in treatment of SSc. Methods: Eleven patients (three males and eight females) with SSc were enrolled. Blood mononuclear cells were harvested after mobilization treatment with CYC and G-CSF. CD34 ⁺ haematopoietic stem/progenitor cell fractions were purified and cryopreserved. Patients were transplanted with >2 × 10/kg autologous CD34 ⁺ cells after high-dose CYC (50 mg/kg for 4 days) conditioning. Immune reconstitution was evaluated serially by analysing lymphocyte subpopulations for 36 months. Results: Progressive improvement of skin sclerosis has been observed for 3 years in most of the patients. The serum level of anti-Scl-70, an auto-antibody specific to SSc, was progressively decreased after ASCT. Improvement of skin sclerosis was significantly associated with the change in the serum anti-Scl-70 level after ASCT at 36 months. Serum levels of KL-6 and surfactant protein D, indicators for interstitial pneumonia activity, were also significantly decreased. The number of CD8+ T cells immediately recovered within a month after ASCT, while the number of CD4+ T cells remained low for >36 months post-transplant. The majority of CD4 ⁺ cells were memory but not naïve T cells, and regulatory CD4 ⁺ T cells were not recovered. Th1/Th2 ratio was significantly increased after ASCT. Conclusions: ASCT with purified CD34 ⁺ cells was effective in controlling the disease activity of SSc. Th1/Th2 ratio was significantly increased for at least 3 years after ASCT.