Total and Ascaris-specific serum
IgE levels were measured in a group of 98 Ascaris-infected children from a slum area of Caracas, Venezuela, in whom the
infections were eliminated by regular treatment for 22 months with the anthelmint
Oxantel/
Pyrantel ('
Quantrel'). The children were re-evaluated at the end of the treatment programme, and then 8 months later, at which time
reinfection was assessed. Total
IgE levels at the beginning of the study were significantly higher in the children who became reinfected
after treatment, compared with those who did not. The anthelmint treatment caused a significant decrease in the total
IgE levels in most of the children, and after a period of 8 months without treatment these continued to decrease in the non-reinfected group, but increased again in the reinfected children. The reverse pattern was found for Ascaris-specific
IgE antibody levels, and in fact an inverse correlation was found between total and anti-Ascaris
IgE levels. Striking associations were found between
reinfection and high pretreatment values of total
IgE, but low levels of specific
IgE antibody. These data support the concept that specific
IgE antibody may participate in the protection against helminthic
infection, and suggest that the polyclonal stimulation of
IgE synthesis caused by these parasites may reduce the effectiveness of such responses. The results also indicate that different individuals have varying propensities to respond polyclonally to the helminths, and this influences their resistance to
infection.