Serum antibody levels and avidities to Escherichia coli O antigens and poliovirus type 1 antigen are increased in children treated for malignant disease

Background. Treatment of malignant disease in children is often associated with low serum immunoglobulin and reduced specific antibody levels. The aim of this study was to investigate if the functional affinity of specific an tibodies in serum and saliva is reduced as well and to evaluate if antigeni c exposure or treatment duration affects this antibody avidity. Procedure. Serum samples were obtained from 45 children and salivary specimens from 30 children with malignant disease. The children were tested either prior to, during, or after chemotherapy. Levels of antibody to E. coli O and to poli ovirus type 1 antigens were determined using an ELISA and isotype-specific relative antibody avidity was measured using thiocyanate to elute antibodie s from solid-phase immobilized antigens. Results. Children with malignant d isease had higher levels and relative avidity indexes of serum antibodies t o both antigens as compared to controls. The duration of treatment and type of malignant disease were unrelated to these parameters. In saliva, the le vel of antibodies to E. coli O antigens, but not to poliovirus type 1 antig en, increased during treatment, Conclusions. Both the amount and avidity of serum antibodies to these antigens are increased in children with malignan t disease. This may be due to a dysregulation of the immune system caused b y the malignancy and seems not to be dependent on exposure. In contrast, th e avidity and levels of these antibodies in saliva seem to correlate with t he presence of antigenic exposure. (C) 1999 Wiley-Liss, Inc.