[The IgG subclass level in children and adolescents with malignant diseases]

Children with malignant disease have an increased risk for bacterial infections. We investigated a possible correlation between septic episodes and decreased IgG subclass levels in 63 patients. At diagnosis 13 of 50 children showed decreased IgG subclass levels: 10x IgG4, 2x IgG1, and 1x IgG3 + IgG4 were reduced. Bone marrow infiltration by tumor cells did not increase the frequency of subclass reductions (4/25 with, 9/25 without bone marrow infiltration). The time course of subclass levels was followed during 37 febrile episodes (mainly fever of unknown origin, septicemia, pneumonia) of 23 children under cytostatic therapy. 6 patients showed transient low IgG subclasses: 2x IgG4, 1x IgG1, 1x IgG3, 1x IgG2 + IgG4, and 1x IgG1 + IgG3 + IgG4. Children with decreased IgG subclass levels appeared to occur more independently of leucopenia. In general, febrile episodes in children with subclass decreases did not last a longer period and did not occur more frequently than in children without IgG subclass deficiencies. In conclusion, the determination of IgG subclasses in cancer children at diagnosis or during chemotherapy did not add substantial information of prognostic or therapeutic relevance.