EFFECT OF ANTHELMINTIC TREATMENT ON THE ALLERGIC REACTIVITY OF CHILDREN IN A TROPICAL SLUM

It is well known that helminthic infection can cause a polyclonal stim ulation 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 evaluat ed the effect of regular anthelmintic treatment, for a period of 22 mo nths, on certain aspects of the allergic reactivity of children in a s lum area of Caracas, Venezuela, where helminths are endemic. The treat ment (Oxantel-Pyrantel,; Quantrel) effectively eliminated intestinal h elminthic infection and resulted in a significant decrease in the init ially elevated total serum IgE levels. IL-4 was detectable in the seru m, and a significant reduction in IL-4 was also observed after treatme nt. In contrast, both the immediate-hypersensitivity skin-test reactiv ity and serum levels of specific IgE antibody against environmental al lergens were markedly increased in the treated children. In a group of children who were also evaluated in the same slum, but who declined t reatment, a substantial increase in helminthic infection occurred, whi ch was related to an acute deterioration of the socioeconomic conditio ns of Venezuela over the course of our study period. This was parallel ed by a considerable increase in total IgE levels in these children an d a decrease in the skin-test reactivities and specific IgE levels. Th e application of Prausnitz-Kustner passive transfer tests and analysis of specific IgE antibody levels indicated that the polyclonal stimula tion of IgE synthesis by helminthic parasites results in mast cell Fce psilon receptor saturation and suppression of specific IgE antibody sy nthesis. This inhibition of allergic reactivity is reversible by anthe lmintic treatment.