Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Asthma is a chronic disease characterized by airway inflammation, obstruction and hyperresponsiveness. Severe asthma affects a small proportion of subjects but results in most of the morbidity, costs and mortality associated with the disease. Studies have suggested that Schistosoma mansoni infection reduces the severity of asthma and prevent atopy. Objective: We evaluated the ability of S. mansoni antigens, Sm29 and Sm29TSP-2 to modulate lymphocyteactivation status in response to the allergen of the mite Dermatophagoides pteronyssinus (Der p1) in cellcultures of individuals with asthma.Methods: Thirty four patients were enrolled in this study: seventeen patients with severe asthma (SAgroup), seventeen patients with mild asthma (MA group) and six controls with no asthma. Peripheralblood mononuclear cells (PBMC) were obtained and stimulated with Sm29 and Sm29TSP-2 in the pres-ence or absence of Der p1. The expression of surface markers and cytokines on lymphocytes was evaluatedby flow cytometry and the levels of IL-10 in the culture supernatant were determined by ELISA.Results: The addition of Sm29 and Sm29TSP-2 antigens to PBMC cultures from both groups of subjectswith asthma stimulated with Der p1 reduced the frequency of CD4+CD25lowcells whereas and increasedfrequency of CD4+CD25highpopulation was observed compared to unstimulated cultures. Moreover, cul-tures stimulated with Sm29TSP-2 showed a reduction in the frequency of T cells expressing CD69, IFN- ,TNF and TGF- in the MA group and an increase in the frequency of CD4+TSLPR+T cells in the SA group.The addition of Sm29 to the cultures reduced the frequency of CD4+CD69+and CD4+IL-5+T cells in all asth-matic groups, and reduced the frequency of CD4+T cells expressing IL-13 in the MA group. The culturesstimulated with Sm29 and Sm29TSP-2 showed an increase in the level of IL-10 in the supernatants.Conclusion: These results suggest that the addition of Sm29 and Sm29TSP-2 to the cells cultures fromsubjects with asthma reduced cell activation markers and altered the cytokine production pattern in away that can potentialy control the inflammatory response associated with asthma