Abstract
The immunomodulatory effect of Schistosoma mansoni antigens has often been attributed to interaction with PRR expressed on APC. Our previous work has shown that S. mansoni-soluble egg antigen (SEA) can induce, together with a Th2 response, TGF-β-dependent Foxp3 expression in naïve CD4(+) T cells from NOD mice. We found that SEA can directly upregulate the expression of surface-bound TGF-β in purified CD4(+) T cells in the absence of accessory cell interactions. In this study, we show that the C-type lectin receptors DEC-205 and galectin-3 were involved in the direct interaction between S. mansoni antigens and CD4(+) T cells. SEA was able to enhance CD4(+) T-cell secretion of bioactive TGF-β in response to TLR2 ligand stimulation, in the absence of APC. We also show that TLR2 expressed on CD4(+) T cells was important for the Foxp3 expression induced by SEA.