The role of T-cell anergy in the immunomodulation of schistosomiasis.

Schistosomes are capable of causing severe tissue damage, which results from the granulomatous inflammation that develops around the parasite eggs. Characteristic of this inflammatory process is its gradual, spontaneous down-regulation (immunomodulation) as the disease progresses. There has been general agreement that the granulomatous inflammation is a consequence of T(H)-cell-mediated delayed-type hypersensitivity to egg antigens. However, the basis of immunomodulation is less clear and has been attributed to various causes. In this review, Miguel Stadecker proposes a novel mechanism of immunomodulation based on the observation that accessory cells from schistosome-infected individuals are capable of inducing a state of unresponsiveness or energy in a subpopulation of antigen-specific CD4(+) T(H)-cell clones identified with delayed-type hypersensitivity reactions.