Cytokine patterns in seropositive and seronegative patients with Echinococcus granulosus infection

To investigate the involvement of immunological variables, including the Th 1/Th2 balance, in the mechanisms underlying seronegativity in cystic echino coccosis (CE), Th1 and Th2 cytokines were evaluated in ELISA determining IF N-gamma, IL-4, -5 and -10 production in peripheral blood mononuclear cell ( PBMC) cultures from 16 patients (six seronegative and ten seropositive) wit h CE and from six healthy donors. Patients who had undetectable antibody le vels in their sera invariably produced no IL-5 and scarce IL-4 and -10 (Th2 response); both groups of patients produced similar amounts of IFN-gamma ( Th1 response). The analysis of host clinical features and cyst characterist ics shows that these variables do not explain the lack of detectable serum antibody levels. These findings suggest that seronegativity arises because unknown host or parasite factors, or both, cause inadequate Th2 cell activa tion thus reducing production of Th2 cytokines, including IL-5, the cytokin e primarily implicated in immunoglobulin expression in CE. (C) 1998 Elsevie r Science B.V. All rights reserved.