RESUMO
Immune reconstitution after allogeneic stem cell transplantation protects against opportunistic infections and disease relapse. Identifying the most protective lymphocyte subset would have implications of adoptive immunotherapy. We followed up a case series of 34 allogeneic transplantations for pediatric leukemias, aplastic anemias, or solid tumors. Regardless of baseline hematologic disorder, the speed of reconstitution of cytotoxic CD8 T lymphocytes and the achieving of the 10th percentile of normal CD4 T lymphocytes (but not B lymphocytes or natural killer cells) conditioned overall survival. The source of hematopoietic stem cells (peripheral blood vs bone marrow) and the occurrence of graft-versus-host disease (either acute or chronic) did not impact on immune reconstitution. Larger case series are needed to confirm the pivotal role of cytotoxic CD8 T lymphocytes in overall survival.