title: Trypanosoma cruzi-induced immunosuppression: B cells undergo spontaneous apoptosis and lipopolysaccharide (LPS) arrests their proliferation during acute infection.
abstract: Acute infection with Trypanosoma cruzi is characterized by multiple manifestations of immunosuppression of both cellular and humoral responses. B cells isolated at the acute stage of infection have shown marked impairment in their response to polyclonal activators in vitro. The present work aims at studying the B cell compartment in the context of acute T. cruzi infection to provide evidence for B cell activation, spontaneous apoptosis and arrest of the cell cycle upon mitogenic stimulation as a mechanism underlying B cell hyporesponse. We found that B cells from acutely infected mice, which fail to respond to the mitogen LPS, showed spontaneous proliferation and production of IgM, indicating a high level of B cell activation. Furthermore, these activated B cells also exhibited an increase in Fas expression and apoptosis in cultures without an exogenous stimulus. On the other hand, B cells from early acute and chronic infected mice did not present activation or apoptosis, and were able to respond properly to the mitogen. Upon in vitro stimulation with LPS, B cells from hyporesponder mice failed to progress through the cell cycle (G0/G1 arrest), nor did they increase the levels of apoptosis. These results indicate that B cell apoptosis and cell cycle arrest could be the mechanisms that control intense B cell expansion, but at the same time could be delaying the emergence of a specific immune response against the parasite.
authors.affiliation: Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ala 1 Subsuelo, Pabellón Argentina, Ciudad Universitaria, Córdoba, Argentina.
authors.forename: E
authors.initials: E
authors.lastname: Zuñiga
authors.forename: C
authors.initials: C
authors.lastname: Motran
authors.forename: C L
authors.initials: CL
authors.lastname: Montes
authors.forename: F L
authors.initials: FL
authors.lastname: Diaz
authors.forename: J L
authors.initials: JL
authors.lastname: Bocco
authors.forename: A
authors.initials: A
authors.lastname: Gruppi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology* / Q000473:pathology; D002455:Cell Division / Q000276:immunology; D014355:Chagas Disease / Q000276:immunology* / Q000473:pathology; D007165:Immunosuppression Therapy; D008070:Lipopolysaccharides / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D014349:Trypanosoma cruzi
chemical_list: D008070:Lipopolysaccharides