The antibody recognition profiles of humans naturally infected with Ascaris lumbricoides

Summary A semi–quantitative analysis of individual human antibody responses to larval Ascaris excretory and secretory (ES) antigens using radioimmunoprecipi–tation and SDS–PAGE is presented. A significant relationship was observed between the intensity of antibody–precipitated radiolabeled ES antigens and host age. The antibody response profile followed a similar age–related pattern to that of intensity of infection, with blood samples from 5–9–year–old children showing the strongest banding patterns and the heaviest infections. These findings support the hypothesis that the degree of exposure to infective stages of Ascaris is a major determinant of the convex age–intensity profile observed in the community. Considerable heterogeneity was observed in the antibody profiles of individuals, particularly in the recognition of a 14 kD molecule. Positive correlations were observed between the strength of banding at several mol. wts and the worm burdens of individuals. However, the sample size was too small to determine whether these relationships simply reflect age–related profiles or represent independent associations between antibody levels and worm burden. When the data were stratified by age, negative associations between the strength of recognition of some bands and the intensity of infection were suggested and require further study.