Purpose: Repeated high-dose chemotherapy (HDCT) followed by peripheral-blood progenitor cell (PBPC) transplantation can induce a complete remission in patients with metastatic breast cancer sensitive to standard chemotherapy (CT), but the majority of patients relapse within 1 to 2 years. The immune system is seriously compromised after HDCT, which precludes the development of effective immunotherapy. We investigated whether autologous lymphocytes, reinfused after HDCT, could induce a rapid recovery of T cells.
Patients and methods: Three patients were monitored for immune recovery without reinfusion of lymphocytes. In the next 11 patients, stem cells were harvested after CT + granulocyte colony-stimulating factor (G-CSF) and lymphocytes were harvested after CT + granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-2. These patients received stem cells and G-CSF after the first HDCT; stem cells, G-CSF, and lymphocytes after the second; and stem cells, GM-CSF, and lymphocytes after the third HDCT.
Results: Patients not receiving lymphocyte reinfusion had a very slow recovery of lymphocytes. In particular, CD4 counts remained low (< 200/microL for 9 months). Lymphocyte reinfusion had a significant effect on the recovery of lymphocytes, T cells, and CD8+ T cells (normalized on day 25). Recovery of CD4+ T cells was significantly accelerated by lymphocyte reinfusion and GM-CSF, leading to counts of 500/microL at 25 days.
Conclusion: Lymphocyte reinfusion with G-CSF had a significant effect on the recovery of CD8+ T cells, whereas rapid recovery of CD4+ T cells required lymphocyte reinfusion and GM-CSF, which possibly acts as a survival factor through activation of antigen presenting cells. Whether the rapid recovery of CD4+ and CD8+ T cells prevents or delays relapse of the disease should be further investigated.