Recovery of Lymphocyte Subpopulations in Children with Hematologic Malignancies after Completion of Chemotherapy

Kim, Hyun Jeong; Yoon, Won Sang; Kim, Chan Jong; Kook, Hoon; Hwang, Tai Ju

Abstract

PURPOSE
Children with cancer are immunosuppressed as a result of the underlying malignancies and their treatment. The aim of this study was to investigate immunophenotypic recovery of lymphocyte populations following completion of treatment in children with hematologic malignancies.
METHODS
Thirty eight patients were followed up to the Department of Pediatrics, Chonnam National University Hospital from Jan. 1995 to Nov. 1999. Using flow cytometry with fluorescein-conjugated monoclonal antibodies of lymphocytes, T-, B-, and Natural killer (NK) cells and CD4/CD8 ratio were enumerated in 38 patients {acute lymphoblastic leukemia (ALL), 19; acute myeloid leukemia (AML), 14; non-Hodgkin's lymphoma (NHL), 5} from 3 months after completion of therapy and every 3 months thereafter over 2 years. The recovery rates of each parameters were compared according to diseases, age and gender.
RESULTS
Absolute lymphocyte count was achieved in 50.0% (19/38) and 73.7% (28/38) of patients at 3 and 12 months after completion of therapy, respectively. Absolute B cell counts as well as the proportion of patients with normal B cell counts were low in NHL than in AML (298+/-250/microliter vs 594+/-356/microliter; P=0.037) at 12 months. T cell recovery tended to be faster in ALL, followed by AML and NHL. NK cell recovery was comparable among 3 disease subgroups. CD4/CD8 ratio was significantly lower in NHL (0.14+/-0.16) than ALL (0.79+/-0.33; P=0.018) at 3 months. CD4/CD8 ratio of NHL (0.41+/-0.14) was lower than ALL (0.79+/-0.29; P=0.033) at 6 months. Differences of CD4/CD8 ratio among the three disease groups were not statistically significant after 9 months. CD4/CD8 ratio was inverted in 22 of 38 (57.9%) patients even after 24 months of therapy. At 12 months higher proportion of male (47.4%, 9/19) achieved a normal CD4/CD8 ratio than that of female (15.8%, 3/19; P=0.036). Age did not make any differences in the recovery.
CONCLUSION
Children with hematologic malignancies have persistent abnormalities of lymphocyte subpopulations often after 2 years following completion of chemotherapy. These results suggest that immunologic assessment are required and that preventive measures for infections might be required for more than 2 years after chemotherapy in some patients. Duration of follow-up observation should be differed according to underlying malignancies and their treatment intensity.