The function of the immune system after the treatment of pediatric malignant diseases

INTRODUCTION: Currently, malignancies in childhood can be cured in 70 percent of the cases. However, the intensive cytostatic therapy may lead to late side effects influencing quality of life. AIM OF THE STUDY: Analysis of the reconvalescence of the immune functions after completion of therapy for malignancies in children. PATIENTS: 88 long-term survivors (51 boys, 37 girls) were investigated (43 acute lymphoid leukemia, 15 lymphoma, 20 bone tumors, 10 other solid tumors). Mean age at the time of diagnosis was 7.8 years (1 mo-17.7 years). METHODS: The following parameters were investigated: serum immunoglobulin levels after completion of the chemotherapy and in the next 4 years thereafter, lymphocyte subpopulations in the peripheral blood by flow-cytometry and cellular immunity by in vitro tests (natural killer activity, antibody-dependent cellular cytotoxicity, mitogen-induced T- and B-cell blastic transformations). RESULTS: Lower serum immunoglobulin (IgG) levels could be detected in patients with leukemia after completion of the chemotherapy (8.8 +/- 3.2 g/l). One year thereafter serum IgG levels increased significantly (10.1 +/- 2.9 g/l) (p<0.05). In patients with solid tumors the serum IgG levels were in the normal range at the end of the chemotherapy (12.1 +/- 4.3 g/l). At a mean of 1.3 years after the end of chemotherapy NK activity decreased in 7/43 (16.3%) leukemia patients, and in 3/45 (6.7%) solid tumor patients, ADCC decreased in 8/43 (18.6%) and 3/45 (6.7%), respectively (p<0.05 leukemia vs. solid tumor). At a mean of 15 months after the end of the therapy B-cell blastic transformation was decreased in 3/43 (7%) leukemia patients and in 4/45 (8.9%) solid tumor patients. At the same time point T-cell blastic transformation was altered in 5/43 (11.6%) and in 4/45 (8.9%) cases, respectively. CONCLUSION: Cytotoxic therapies lead to severe, long-term depression of the immune system. At the end of the chemotherapy this effect is more pronounced in leukemia patients. Years (1.5-3) after completion of the therapy in a significant proportion of the patients some in vitro parameters of the immune system are yet altered, so careful monitoring of this patient population is mandatory.