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

Abstract

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 antibodies in serum and saliva is reduced as well and to evaluate if antigenic exposure or treatment duration affects this antibody avidity. 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 poliovirus type 1 antigens were determined using an ELISA and isotype-specific relative antibody avidity was measured using thiocyanate to elute antibodies from solid-phase immobilized antigens. Children with malignant disease had higher levels and relative avidity indexes of serum antibodies to both antigens as compared to controls. The duration of treatment and type of malignant disease were unrelated to these parameters. In saliva, the level of antibodies to E. coli O antigens, but not to poliovirus type 1 antigen, increased during treatment. Both the amount and avidity of serum antibodies to these antigens are increased in children with malignant disease. This may be due to a dysregulation of the immune system caused by the malignancy and seems not to be dependent on exposure. In contrast, the avidity and levels of these antibodies in saliva seem to correlate with the presence of antigenic exposure.