Human schistosomiasis mansoni: studies on in vitro granuloma modulation.

Infection with Schistosoma mansoni induces humoral and T cell mediated responses and leads to a delayed hypersensitivity that results in granulomatous inflammatory disease around the parasite eggs. Regulation of these responses resulting in a reduction in this anti-egg inflammatory disease is apparently determined by idiotypic repertoires of the patient, associated with genetic background and multiple external factors. We have previously reported on idiotype/anti-idiotype-receptor interactions in clinical human schistosomiasis. These findings support a hypothesis that anti-SEA cross-reactive idiotypes develop in some patients during the course of a chronic infection and participate in regulation of anti-SEA cellular immune responses. We report here on experiments which extend those observations to the regulation of granulomatous hypersensitivity measured by an in vitro granuloma model. T cells from chronic intestinal schistosomiasis patients were stimulated in vitro with anti-SEA idiotypes and assayed in an autologous in vitro granuloma assay for modulation of granuloma formation. These anti-SEA idiotype reactive T cells were capable of regulating autologous in vitro granuloma formation. Both CD4 and CD8 T cells could be activated to regulate granuloma formation. This regulatory activity, initiated with stimulatory anti-SEA idiotypic antibodies, was antigenically specific and was dependent on the presence of intact (F(ab')2) immunoglobulin molecules. The ability to elicit this regulatory activity appears to be dose dependent and is more easily demonstrated in chronically infected intestinal patients or SEA sensitized individuals.(ABSTRACT TRUNCATED AT 250 WORDS)