It is well known that helminthic
infection can cause a polyclonal stimulation of the synthesis of
IgE, which is dependent on
interleukin-4 (IL-4) production, and it has been suggested that this can modulate the expression of allergic reactivity in tropical populations. We evaluated the effect of regular
anthelmintic treatment, for a period of 22 months, on certain aspects of the allergic reactivity of children in a slum area of Caracas, Venezuela, where helminths are endemic. The treatment (
Oxantel-
Pyrantel;
Quantrel) effectively eliminated intestinal helminthic
infection and resulted in a significant decrease in the initially elevated total serum
IgE levels.
IL-4 was detectable in the serum, and a significant reduction in
IL-4 was also observed
after treatment. In contrast, both the
immediate-hypersensitivity skin-test reactivity and serum levels of specific
IgE antibody against environmental
allergens were markedly increased in the treated children. In a group of children who were also evaluated in the same slum, but who declined treatment, a substantial increase in helminthic
infection occurred, which was related to an acute deterioration of the socioeconomic conditions of Venezuela over the course of our study period. This was paralleled by a considerable increase in total
IgE levels in these children and a decrease in the skin-test reactivities and specific
IgE levels. The application of Prausnitz-Küstner passive transfer tests and analysis of specific
IgE antibody levels indicated that the polyclonal stimulation of
IgE synthesis by helminthic parasites results in mast cell
Fc epsilon receptor saturation and suppression of specific
IgE antibody synthesis. This inhibition of allergic reactivity is reversible by
anthelmintic treatment.