Evaluation of cellular immune response during chronic schistosomiasis in humans by the leukocyte aggregation test and the leukocyte migration inhibition test.

Cellular immune response was evaluated in 31 patients with chronic Schistosoma haematobium and Schistosoma mansoni infections and in 15 healthy normal persons by using S. mansoni soluble worm and egg antigens. Although the leukocyte migration inhibition test demonstrated false-positive reactions, the specificity of the leukocyte aggregation test was confirmed by the negativity of all of the controls. Among the patients, only 10% were positive for the leukocyte aggregation test. This low cellular reactivity was in contrast to markedly elevated specific humoral response determined by an enzyme-linked immunosorbent assay for immunoglobulin G and paper allergosorbent test for immunoglobulin E with soluble worm antigen. These results confirm that the cellular immune reactivity to schistosome antigen as demonstrated by the leukocyte aggregation test is either minimal or absent in chronically infected patients.