Immune Dysfunction After Completion of Childhood Leukemia Therapy.

BACKGROUND: Children with leukemia suffer immune dysfunction from their malignancy and chemotherapy. The immune system components most affected, the degree to which immune suppression occurs, and the duration of immunodeficiency are incompletely characterized. This study measures immunologic parameters following completion of therapy.
METHODS: This is a prospective, single institution cohort study. Eligible children with acute myelogenous or acute lymphoblastic leukemia diagnosed between 1 and 21 years of age were enrolled at therapy completion. Immune parameters were assessed at the end of therapy and 6 months later: complete blood counts, immunoglobulin levels, quantitative lymphocyte subsets, mitogen-induced lymphocyte proliferation, natural killer cell function, and vaccine titers.
RESULTS: Twenty patients were evaluated; 13 (65%) were female, 15 had acute lymphoblastic leukemia (75%). Mean age at diagnosis was 7.9 years. At end of therapy, all patients had some degree of immune dysfunction. At 6 months posttherapy, persistent abnormalities included: leukopenia (25%), neutropenia (15%), lymphopenia (5%), hypogammaglobulinemia (25%), one or more subtherapeutic vaccine titers (100%), abnormal lymphocyte subset levels (20%), decreased (15%), or absent (10%) natural killer cell function and abnormal lymphocyte proliferative responses (25%).
CONCLUSIONS: All patients had multiple abnormalities at end of therapy, and all patients had some degree of persistent immune dysfunction at 6 months after completion of therapy. Clinical implications of these laboratory abnormalities are currently unknown; longer term evaluations are ongoing. We demonstrate that survivors of childhood cancer have lasting quantitative and functional immunologic defects and may remain at risk for infectious complications after completion of therapy.