Antifilarial IgG4 antibodies in children from filaria-endemic areas correlate with duration of infection and are dissociated from antifilarial IgE antibodies.

To investigate the relationship of antifilarial IgG4 and IgE to the intensity of transmission and duration of filarial infections in endemic populations, antifilarial antibody levels in children residing in a village in Papua New Guinea where transmission of Wuchereria bancrofti was reduced by repeated insecticide spraying were compared with levels in residents of three nearby villages where no control measures had been used. Antifilarial IgG4 levels were significantly lower in children from the sprayed village than in children or adults in nonsprayed villages (P < .01) and correlated with age (P < .05) and intensity of microfilaremia (P < .01). In contrast, antifilarial IgE was elevated to similar levels in children and adults from both villages. Antifilarial IgG4 (and not IgE) levels in endemic populations appear to be directly related to the duration of infection or to the cumulative exposure to infective vectors.