A study of immunoregulation of BALB/c mice by Echinococcus granulosus equinus during prolonged infection.

Two models of intraperitoneal infection with E. granulosus equinus by protoscolices and by cyst passage in BALB/c mice were used to provide mesenteric lymph node cells for adoptive cell transfer into syngeneic recipient normal responder mice. The cell transfer inocula were shown to have depleted Thy-1 cells, but to be highly suppressive to the normal sheep erythrocyte response of the recipients. The nature of the depletion and non-specific suppression, and the infectious nature of the latter, are discussed in relation to other examples of mitogenic stimulation resulting in non-specific T cell suppressor activity. The functions of Ly-2,3+ cells, not only as suppressor, but as alloreactive cytotoxic cells, are discussed as a possible, autoimmune explanation for the longevity of the parasite within the mouse model, in contradistinction to the predictable early rejection of analogous xenografts.