Background: The bone marrow transplantation (BMT) is an effective treatment for patients with several hematologic diseases. However, most studies for immune reconstitution after BMT are limited to immunophenotyping of lymphocytes in the peripheral blood and little information about cell surface antigen expression and distribution of the nucleated elements in the bone marrow after BMT have been published. To set up baseline data for bone marrow recovery after BMT, we investigated reconstitution of the bone marrow at 21th day after allogeneic and autologous BMT.
Method: The flow cytometric analyses for 17 monoclonal antibodies in the 35 bone marrow transplant recipients (allogeneic BMT 25, autologous BMT 10) and 20 healthy donors of allogeneic BMT were performed. The percentage of positive cell population was calculated in the gated region and compared data for BMT vs normal controls and allogeneic vs autologous BMT.
Result: CD8+ T cell and CD56+ NK cell were the first signs of immunological recovery at 21th day after BMT, whereas the CD4+ subsets were significantly decreased. These findings were prominent in the autologous BMT. After BMT, the CD2+CD5- cell population was characteristically increased. All B cell markers were decreased and most lympocytes were expressed HLA-DR. The donor's immunophenotypes before BMT did not correlate with the recipient's immunophenotypes after BMT.
Conclusions: We demonstrated that the CD8+ T cells and NK cells were main cell populations in the bone marrow for primary immunological defences at 21th day after BMT and these finding s were more distinct in the autologous BMT than the allogeneic BMT. It indicated that there were more rapid reconstitution in the autologous BMT. The B cell recovery was delayed rather than T cell and increased CD2+CD5- cell population was characteristic finding in post-BMT.

Keywords: BMT, Flow cytometry, Immune reconstitution, Lymphocyte subset