Delayed type hypersensitivity granuloma formation around Schistosoma mansoni eggs in vitro. IV. Granuloma formation in human schistosomiasis.

Peripheral blood mononuclear cells, obtained from 42 school-age Egyptian children, were isolated on Ficoll-hypaque density gradients and assayed for granuloma formation. A granuloma index (G.I.) which classified the cellular reactions to Schistosoma mansoni eggs was determined for each patient. Morphologic criteria to assess the cellular reactivity included cell adherence, blast cell transformation, cell migration, and circumoval accumulation of inflammatory cells around the egg. The difference between the mean granuloma index of uninfected controls (G.I. = 1.25 +/- 0.04) and infected patients (G.I. = 1.58 +/- 0.05) was statistically significant (P less than 0.01; Student's t-test). There was no correlation between the granuloma indices and infection intensities determined by quantitative egg counts or between anti-major serological antigen antibody titers. These data demonstrate the feasibility of studying granulomatous hypersensitivity in human schistosomiasis utilizing an in vitro model of granuloma formation and peripheral blood cells.