The role of the thymus in modulating gammadelta T cell suppressor activity during experimental Trypanosoma cruzi infection.
We have previously shown that splenic gammadelta T cells from young but not aged BALB/c mice possess suppressor activity in vivo and in vitro during the acute phase of Trypanosoma cruzi infection. The present work was undertaken to investigate the suppressor activity of gammadelta T cells from T. cruzi-infected euthymic or athymic mice and the role of the thymus in modulating non-adherent spleen cell suppressor activity during the acute phase of infection. Splenic gammadelta T cells from aged or athymic BALB/c mice reconstituted with total spleen cells or non-reconstituted did not exhibit suppressor activity when added to full allogeneic, mixed lymphocyte cultures. In contrast, splenic gammadelta T cells from young euthymic BALB/c mice showed suppressor activity in vitro. Thymectomy reduced the splenic gammadelta T cell suppressor activity of young BALB/c mice in a time-dependent manner, following a T. cruzi challenge. The continuous provision of thymocytes to aged mice, young thymectomized mice or total spleen cell-reconstituted athymic mice could re-establish the gammadelta T cell suppressor activity. Of particular significance was the observation that the depletion of gammadelta T cells during the acute phase of T. cruzi infection restored the capacity of these mice to mount a humoral immune response to a non-related antigen such as ovalbumin. These results indicate that gammadelta T cells of extrathymic origin cannot mediate suppression and that the thymus has a role in the regulation of suppression during the acute phase of T. cruzi infection.
Cardillo
F
F
Department of Immunology, Institute of Biological Sciences, University of São Paulo, SP, Brazil.
Nomizo
A
A
Mengel
J
J
D000208:Acute Disease; D000375:Aging; D000818:Animals; D000917:Antibody Formation; D014355:Chagas Disease / Q000276:immunology* / Q000469:parasitology; D007111:Immunity, Cellular; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D010047:Ovalbumin / Q000276:immunology; D013154:Spleen / Q000166:cytology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D013934:Thymectomy; D013950:Thymus Gland / Q000276:immunology*; D014349:Trypanosoma cruzi
D010047:Ovalbumin