IL-10 PLAYS A ROLE IN THE MODULATION OF HUMAN GRANULOMATOUS HYPERSENSITIVITY AGAINST SCHISTOSOMA-MANSONI EGGS INDUCED BY IMMUNE-COMPLEXES

It has been demonstrated that the chronic intestinal form of schistoso miasis is associated with the establishment and maintenance of a varie ty of immunoregulatory mechanisms that lead to a diminished granulomat ous reaction to parasite eggs. Using an in vitro model of granuloma re action we showed that immune complexes (IC) isolated from the sera of chronic intestinal schistosomiasis patients were able to reduce the gr anulomatous hypersensitivity (developed by peripheral blood mononuclea r cells (PBMC) from schistosomiasis patients) to soluble egg antigen ( SEA)-conjugated polyacrylamide beads (PB-SEA). This inhibitory activit y, mediated by IC, was also observed in the proliferative response of PBMC stimulated with SEA and soluble worm antigen preparation (SWAP). Furthermore, we observed a decrease in TNF-alpha and an increase in IL -10 production by PBMC treated with IC in an in vitro granuloma reacti on. This phenomenon was also seen in a cell proliferation assay when P BMC were treated with IC and stimulated with S. mansoni antigens. Thes e results demonstrate that circulating IC may down-regulate PBMC react ivity to S. mansoni antigens by changing the cytokine pattern produced by these cells.