Late immune recovery in children treated for malignant diseases.

In this study we analyzed the recovery of the immune system in children after completion of the therapy. We analysed 88 children (51 boys, 37 girls, mean age at diagnosis: 7.8 years) receiving chemotherapy for malignant diseases (43 acute lymphoblastic leukemia, 15 lymphoma, 20 bone tumor, ten other solid tumors). Serum immunoglobulin levels (Ig), natural killer activity (NK), antibody-dependent cellular cytotoxicity (ADCC) and T and B cell proliferation were determined 1 year after cessation of therapy. The mean levels of Ig were in the normal range at a mean of 13 months after chemotherapy (IgG: 11.2 +/- 3.3, IgA: 1.6 +/- 0.9, IgM: 1.0 +/- 0.5 g/l), however in the leukemic patients serum IgG was below the lower limit of the normal range in 3/43 (7.0%) cases, serum IgA was low in 5/43 (11.6%) and serum IgM was decreased in 4/43 (9.3%) cases. In the solid tumor patients IgG values were within the normal range and only 2-2/45 children had lower values for IgA and IgM (4.4%). NK activity decreased in 7/43 (16.3%) leukemic patients, and in 3/45 (6.7%) solid tumor patients, ADCC decreased in 8/43 (18.6%) and 3/45 (6.7%), respectively (p < 0.001). B-cell blastic transformation was decreased in 3/43 (7%) leukemic patients and in 4/45 (8.9%) solid tumor patients. At the same time T-cell blastic transformation was altered in 5/43 (11.6%) and in 4/45 (8.9%) cases, respectively. Leukemic patients had significantly more infections during the first year after chemotherapy than solid tumor patients (1.60 +/- 1.18 vs 0.96 +/- 1.14; p = 0.011). No significant correlations could be found between the investigated immune parameters and the number and severity of infections. It is concluded, that cytotoxic therapy can lead to long-term depression of the immune system, first of all in leukemic patients.