Hyperimmunoglobulinemia E in the Waorani, an isolated Amerindian population.

The Waorani Indians of Eastern Ecuador have the highest blood levels of immunoglobulin E that have been recorded in a human population. Using a radial immunodiffusion technique for IgE determination, we found the mean plasma IgE concentration for the entire sample (n = 227) to be 11,975 International Units per milliliter (normal: 5--500 IU/ml). The reason for the elevated IgE concentrations is unclear, although genetic factors and a high prevalence of parasitic infection may be involved. Atopic disease is rare among the Waorani as determined by medical history, physical examination, and immediate hypersensitivity skin tests. Our data are consistent with the association between hyperimmunoglobulinemia E and low prevalence of atopic disease in tropical populations. The significance of the findings with regard to the control of allergic disorders is discussed.