A Specific Circulating Antigen in Hamsters Infected with Schistosoma Mansoni

Detection of Antigen in Serum and Urine, and Correlation between Antigenic Concentration and Worm Burden

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  • Department of Tropical Public Health, Harvard School of Public Health, and the Laboratory of Immunology, Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02115

A specific schistosomal antigen in the serum of animals heavily infected with Schistosoma mansoni has recently been detected by immunodiffusion and immunoelectrophoresis. Evidence now obtained by radial diffusion methods indicates a direct relation between the number of worms in the hamster and the amount of antigen in its serum. Preliminary characterization of this antigen was undertaken by concentrating immunologically identical materials from worm extracts with preparative starch-block electrophoresis. The antigen was heat-stable, dialyzable, and had a molecular weight of less than 10,000. Despite an ultraviolet absorption peak of 260 mµ, the antigen showed no change in absorption pattern or behavior on a Sephadex column after incubation with deoxyribonuclease or ribonuclease; neither ribose nor deoxyribose was detectable by paper chromatography. Immunodiffusion studies with urine specimens from infected animals indicated the occasional presence of small amounts of specific antigen identical to that in the serum. When urine from infected animals was reacted with serum from the same or from other infected hamsters, additional precipitin lines were revealed. The latter were not obtained with serum from normal hamsters nor with antiserum prepared in rabbits by injection of worm extracts, nor could the responsible antigens be identified with those in extracts of schistosomes.

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