<b><i>Schistosoma</i></b> Antigens Downmodulate the in vitro Inflammatory Response in Individuals Infected with Human T Cell Lymphotropic Virus Type 1

Human T cell lymphotropic virus type 1 (HTLV-1) is the causal agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). While the immune response to HTLV-1 infection is polarized to the Th1-type, chronic helminth infections drive the Th2- and T regulatory-type, and are able to downregulate the inflammatory response in some autoimmune diseases. <b><i>Objective:</i></b> To evaluate whether <i>Schistosoma </i>spp. antigens alter the in vitro cytokine response in HTLV-1 infection. <b><i>Methods:</i></b> The recombinant <i>Schistosoma</i> antigens Sm29 and ShTSP2 (tetraspanin) and PIII, a fraction of <i>the Schistosoma mansoni</i> adult worm antigen were added to peripheral blood mononuclear cell (PBMC) cultures of HTLV-1-infected individuals and the levels of interferon (IFN)-&#947; and interleukin (IL)-10 in the supernatants were measured using the ELISA sandwich technique. <b><i>Results:</i></b> Compared to the levels of cytokine in nonstimulated cultures, the levels of IFN-&#947; were reduced in 50, 47 and 50% of patients by the presence of Sm29, ShTsp2 and PIII, respectively. The downregulation of IFN-&#947; production in the presence of Sm29 antigen was observed mainly in subjects who had lower basal levels of this cytokine. The levels of IL-10, however, increased by the addition of the three antigens in the cultures in 74, 62 and 44% of individuals, respectively. In addition, there was a decrease in the ratio of IFN-&#947;/IL-10 levels in cultures stimulated with Sm29 and ShTSP2 when compared to nonstimulated ones. <b><i>Conclusions:</i></b> The <i>Schistosoma </i>spp. antigens used in this study were able to downmodulate IFN-&#947; production in vitro in HTLV-1 infection. This may be associated with the increased levels of IL-10 induced by the antigens.