TYPE-1 AND TYPE-2 CYTOKINE-PRODUCING MOUSE CD4(-CELLS IN ACUTE SCHISTOSOMA-MANSONI INFECTION() AND CD8(+) T)

CD4(+) and CD8(+) T cells can be divided based on the cytokines that t hey secrete into type 1 (Th1, Tc1) and type 2 (Th2, Tc2) subsets. Schi stosoma mansoni infection in mice is characterized by a type 2-dominat ed response. We have used intracellular cytokine staining to demonstra te dramatic changes in the relative numbers of Tc1 and Th2 cells in th e spleens of mice during acute schistosome infection. In infected mice prior to egg laying a generalized type 1 response dominated, and was associated with an expansion in the frequency of Tc1 and Th1 cells. By week 7 after infection the cytokine response was of type 2, with an i ncrease in the numbers of Th2 cells and a dramatic reduction in the fr equency of Tc1 cells. Following the onset of egg laying there was apop tosis of cells in the spleens of mice, with CD4(+) and in particular C D8(+) T cells undergoing apoptosis. The loss of CD8(+) T cells may in part be attributable to the development of a type 2 environment, follo wing egg laying, with type 2 responses mediating the apoptosis of Tc1 cells. Schistosoma regulation of Tc1 during egg laying may be required to prevent type 1 inflammatory responses from exacerbating egg-induce d pathology.