IngentaConnect Trypanosoma cruzi-induced immunosuppression: B cells undergo spon...

Authors: Zuñiga, E.¹; Motran, C.¹; Montes, C. L.¹; Diaz, F. L.¹; Bocco, J. L.¹; Gruppi, A.¹

Source: Clinical & Experimental Immunology, Volume 119, Number 3, March 2000 , pp. 507-515(9)

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.

Keywords: Trypanosoma cruzi; B lymphocytes; immunosuppression; apoptosis; cell cycle arrest

Document Type: Research article

DOI: 10.1046/j.1365-2249.2000.01150.x

Affiliations: 1: Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ala 1 Subsuelo, Pabellón Argentina, Ciudad Universitaria, Córdoba, Argentina

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Trypanosoma cruzi-induced immunosuppression: B cells undergo spontaneous apoptosis and lipopolysaccharide (LPS) arrests their proliferation during acute infection