Inhibition of immediate and Arthus responses to schistosome egg antigens by T cells from Schistosoma japonicum-infected mice.

Schistosoma japonicum-infected mice develop hepatic granulomas, immediate hypersensitivity (IH), and delayed hypersensitivity (DH) to soluble egg antigens (SEA) released by parasite eggs trapped in liver sinusoids. All of these responses spontaneously regress after 7 to 9 weeks of infection. This study aimed to develop an in vivo system for the further dissection of cellular and humoral immune responses to SEA. C57BL/6 mice immunized subcutaneously with SEA in complete Freund adjuvant developed IH, an Arthus reaction, and DH to this antigen 5 to 9 days later. IH and the Arthus reaction, but not DH, were markedly inhibited if, 1 day before injection of SEA in complete Freund adjuvant, the mice were injected intravenously with purified T cells from the spleens of mice infected for at least 9 weeks. This in vivo model system can be used to study various aspects of cellular and humoral immune responses to SEA and their modulation. These results raise questions about the role of antibodies in the pathogenesis of granulomatous inflammation and about the mechanisms of its cellular regulation in infections with S. japonicum.