Anti-schistosome IgG4 and IgE at 2 years after chemotherapy: infected versus uninfected individuals.

Specific IgG4 and IgE responses to adult worm antigen (AWA) and soluble egg antigen (SEA) were examined in 37 subjects from an area in which schistosomiasis is endemic, who were previously infected with Schistosoma haematobium and who became reinfected or remained free of infection 2 years after chemotherapy. The reinfected group was significantly younger (median age, 11 years) than the uninfected group (median age, 24 years). Posttreatment levels of IgG4 to egg antigens (IgG4-SEA) were significantly correlated with reinfection intensity (r = .74, P < .0001), and 13-fold lower levels of IgG4-SEA were observed in uninfected subjects compared with reinfected subjects. Although no correlation was observed between posttreatment IgE to AWA or to SEA, pretreatment IgE-AWA was inversely correlated with the level of reinfection (r = -.39, P = .02).