Previously, we have demonstrated that BALB/c mice immunized with cruzipain (Cz), a major Trypanosoma cruzi antigen, produce specific and autoreactive immune response against heart antigens associated with cardiac functional and structural abnormalities. Preferential activation of Th2 phenotype and an increase in cell populations expressing CD19+, Mac-1+ and Gr-1+ cell markers were found in the spleens of BALB/c mice.
Objective: The aim of the present study was to investigate the immune response elicited by Cz in C57BL/6 (B6) mice and to elucidate whether it is implicated in cardiac autoimmnity and pathology.
Methods: B6 and BALB/c mice, aged 6-8 weeks were immunized on days 0, 14 and 28 by i.d. injection with irreversibly inactivated cruzipain-10 mg (Immune group) or OVA-10 ug (Control group) or recombinant trans-sialidase (rTS)-10 mg emulsified in CFA.
Results: We demonstrate that immune B6 splenocytes, restimulated in vitro with Cz, produced high levels of IFNg (6,313± 2,300 pg/ml) and low levels of IL-4 (261± 105 pg/ml) compatible with a Th1 profile. We also show that the immunization with rTS elicited different cytokine profiles to those found with Cz in B6 and BALB/c mice. Spleens from Cz immune B6 mice revealed no significant changes in the number of cells presenting CD19+, Mac-1+ and Gr-1+ markers. An increased secretion of TGFb (immune B6 5,542± 600 vs immune BALB/c 870± 160pg/ml) and a greater number of CD4+ TGFb+ cells were found in immune B6 (35%) but not in BALB/c (6%) mice. These findings were associated with the lack of autoreactive response against heart myosin in contrast to the results found in Cz immune BALB/c mice.
Conclusion: The results suggest that immune response to T. cruzi antigens, Cz and TS are differentially modulated in B6 and BALB/c mice which are implicated in the resistance or pathogenic mechanisms of experimental Chagas disease.
