Antibody isotype responses to antigens of Ascaris lumbricoides in a case-control study of persistently heavily infected Bangladeshi children.

Antibody responses to Ascaris lumbricoides worm antigens were examined by ELISA in a case-control study of 2 groups of Bangladeshi children, one of which had been shown over a period of 12 months to be consistently lightly infected (controls) and the other consistently heavily infected (cases). The children showed a wide range in intensity of infection; children identified as cases were on average 4 times more heavily infected than the controls. There were no significant differences in weight, height, mid-upper arm circumference and skinfold thickness between the case or control subjects at the time blood samples for analyses by ELISA were collected. Children with repeatedly heavy infections with A. lumbricoides had higher concentrations of antibody isotypes to the antigens of A. lumbricoides than children who are repeatedly lightly infected. IgG1, IgG4 and IgE to worm antigens occurred in significantly higher concentrations in heavily infected subjects. This suggests that these antibody responses simply reflect the intensity of infection and may not play a significant role in protecting against heavy infections.