Antischistosome IgG4 and IgE responses are affected differentially by chemotherapy in children versus adults

Specific IgG4 and IgE responses and polyclonal cytokine profiles were studied in 110 Schistosoma haematobium- infected persons before and 5 weeks after chemotherapy. Pretreatment IgG4 re-sponses to soluble egg antigen (SEA) correlated with intensity of infection. After chemotherapy, a significant decrease in egg output and circulating anodic antigen was associated with a substantial drop in the IgG4 response to SEA (IgG4-SEA) in adults and in children, suggesting that egg laying is a major stimulus for IgG4-SEA. After chemotherapy, IgG4 and IgE to adult worm antigen and IgE to SEA increased in children but remained unchanged in adults. This indicates that the immunoregulatory mechanisms operative in S. haematobium- infected adults differ from those in infected children. The effect of treatment on cytokine profiles was determined following stimulation of whole blood with anti-CD3 antibodies. A significant decrease in interleukin-4 production after treatment indicated that reduction in helminth load may lead to a reduced number of Th2-type cells. Human infection with schistosomes characteristically results in heightened IgE and IgG4 responses, isotypes that are nor-mally expressed at very low levels. The balance between thes