The molecular basis of granuloma formation in schistosomiasis. I. A T cell-derived suppressor effector factor.

These studies define certain T cell-dependent regulatory factors that modulate granulomatous hypersensitivity in Schistosoma mansoni. Lyt-2+ and IJ+ T cells produce a suppressor effector factor (TseF) that bears both an IJ determinant and an antigenically specific receptor. TseF suppresses in vitro and in vivo granulomatous hypersensitivity and demonstrates both antigenic and genetic restriction. This factor binds to the mAb 14-12 but not 14-30 suggesting that it also bears a specific suppressor effector phenotypic marker. Factor production is abrogated by the addition of exogenous IL-2; however, the activity of preformed TseF is not affected by IL-2. Initial characterization studies have suggested that TseF is a non-Ig protein and that it is composed of two chains that can be separated by dithiothreitol reduction. These chains can complement each other by in vitro reconstitution of reactivity. One chain bears the IJ phenotype. The other chain bears the Ag-R. Thus it would appear that this TseF bears strong structural homologies to those previously ascribed to T cell-R. These studies provide preliminary information on the molecules that are responsible for the specific modulation of granulomatous hypersensitivity in schistosomiasis.