Printed in U.S.A. ENZYME- AND 1251-LABELED ANTI-IMMUNOGLOBULIN ASSAYS IN THE IMMUNODIAGNOSIS OF SCHISTOSOMIASIS*

Abstract.An enzyme-linkedimmunosorbentassay(ELISA),and radioimmunoassaysusing antigen bound to plastic tubes or microcrystalline partides, were adapted for the indirect serological measurement of anti-schistosome antibodies. These alkaline phosphatase and 125I labeled anti-immunoglobulin techniques were found to be highly quantitative and adaptable. Comparison showed them to be considerably more sensitive than the indirect hemagglutination and indirect fluorescent antibody techniques. Using adult S. mansoni freeze-thaw antigen, anti-schistosome antibodies were detected in sera from patients infected with Schistosoma mansoniand S.haematobium.However,resultsinpatientswithschistosomiasishaematobium were generally intermediate between those of patients with schistosomiasis mansoni and normal, uninfected controls. Since Bilharz first discovered Schistosoma worms in the cadaver of a young Egyptian in 1851, schistosomiasis has become recognized as one of the most important infectious diseases of man with some 180 to 200 million people currently known to be infected. ' Although information is accumulating that specific anti-schistosome anti bodies are a major factor in the development of acquired resistance to this disease,2 current proce dures for assessing these antibodies in clinical or epidemiological specimens are relatively insen sitive.3'4 In addition, the correlation between serological results and levels of resistance or clinical disease in individuals is poor.5 Highly sensitive assay systems which employ antibodies labeled with radioisotopes or enzymes are currently being used to measure more accu rately the amount of antibody involved in i