Immune re-constitution after allogeneic hematopoietic stem cell transplantation in patients with hematological malignancies

Abstract

Objective To study the immune re-constitution after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with hematological malignancies. Methods From June 2011 to May 2015, 65 patients with hematological malignancies were analyzed retrospectively. Lymphocyte subsets were determined by flow cytometry (FCM), including total T lymphocytes (CD3+ ), helper T cells (CD3+ CD4+ ), cytotoxic T cells (CD3+ CD8+ ), CD4/CD8 ratio, nature killer (NK) cells (CD3-CD56+ ), NKT cells (CD3+ CD56+ ), B lymphocytes (CD19+ ), naive T cells (CD3+ HLA-DR+ ), static T cells (CD3+ HLA-DR-), and regulatory T cells (CD4+ CD25highFoxp3+ ) on the day 14, 28 and 42, and on the month 2, 3, 6, 9, 12, 15, 18 and 24 after allo-HSCT. Results The percentage of CD3+ T cells located normal range after hematological recovery, and its absolute number recovered to normal range at + 15 months. The percentage of CD3+ CD4+ T cells recovered to normal range at + 24 months. However, the absolute number of CD3+ CD4+ T cells did not recover to normal range until 24 months after allo-HSCT. The percentage of CD3+ CD8+ T cells was higher than normal range at + 42 day, and its absolute number was greater than normal range at + 3 months. Hence, low CD4/CD8 ratio was observed for a long period. The re-constitution time points of the percentage and absolute number of CD3+ HLA-DR+ T cells were + 3 months and + 24 months respectively. The re-constitution time points of the percentage and absolute number of CD3+ HLA-DR-T cells were + 2 months and + 15 months respectively. The re-constitution time points of the percentage and absolute number of regulatory T cells were + 12 months and + 15 months respectively. The percentage of NKT cells located in normal range after hematological recovery, and its absolute number returned to normal range at + 12 months. The re-constitution time points of the percentage and absolute number of B cells were + 9 months and + 18 months respectively. The percentage of NK cells located in normal range after hematological recovery, and its absolute number returned nearly to normal range at + 3 months. Conditioning regimen containing ATG, source of stem cells, CD34+ cell number, GVHD, and CMV reactivation were all associated with immune re-constitution after allo-HSCT. Conclusion Different immune cells showed different re-constitution models after allo-HSCT, and the percentage recovered faster than absolute number for a certain kind of immune cells. Studying immune re-constitution and its associated factors may offer beneficial information for insight into transplantation immunology and improve the management of allo-HSCT. Key words: Hematological malignancies; Hematopoietic stem cell transplantation; Immune reconstitution