Immune reconstitution after autologous purged bone marrow transplantation in children

Immune reconstitution was studied in 30 children who had received purged autologous bone marrow transplantation for neuroblastoma or acute myeloid leukemia (AML).

Patients with neuroblastoma received high-dose chemotherapy and total body irradiation, and patients with AML received chemotherapy alone. Marrows were purged ex vivo with either antineuroblastoma monoclonal antibodies (neuroblastoma) or 4-hydroperoxycyclophosphamide (AML). Lymphocyte subsets, mitogen stimulation studies, and immunoglobulin levels were studied every 4 months.

There were no significant differences between the two groups of patients in lymphocyte number or subsets over time. In both groups, CD2+ and CD4+ cells were below normal in 33% of patients at 12 months. CD4+/CD8+ ratios were below normal for up to 8 months after transplantation and natural killer cells were elevated for up to 2 years in most patients. Median IgG and IgA levels were below the age mean even at 2 years after transplantation, although patients with AML had significantly higher IgG levels at 12 months compared with those with neuroblastoma. Lymphocyte proliferative responses to mitogens were markedly reduced at 4 months but returned to normal at 8 months. Despite the delay in immune reconstitution, there were no life-threatening infections.

There appeared to be little difference in the overall kinetics of immune reconstitution between the children with neuroblastoma, who received total body irradiation and high-dose chemotherapy, and those with AML, who received high-dose chemotherapy alone as their pretransplant preparative regimen.