CTLA-4 and CD4+ CD25+ regulatory T cells inhibit protective immunity to filarial parasites in vivo

Taylor, M.D., Harris, A., Babayan, S.A. , Bain, O., Culshaw, A., Allen, J.E. and Maizels, R.M. (2007) CTLA-4 and CD4+ CD25+ regulatory T cells inhibit protective immunity to filarial parasites in vivo. Journal of Immunology, 179(7), pp. 4626-4634.

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Publisher's URL: http://www.jimmunol.org/content/179/7/4626.long


The T cell coinhibitory receptor CTLA-4 has been implicated in the down-regulation of T cell function that is a quintessential feature of chronic human filarial infections. In a laboratory model of filariasis, Litomosoides sigmodontis infection of susceptible BALB/c mice, we have previously shown that susceptibility is linked both to a CD4+ CD25+ regulatory T (Treg) cell response, and to the development of hyporesponsive CD4+ T cells at the infection site, the pleural cavity. We now provide evidence that L. sigmodontis infection drives the proliferation and activation of CD4+ Foxp3+ Treg cells in vivo, demonstrated by increased uptake of BrdU and increased expression of CTLA-4, Foxp3, GITR, and CD25 compared with naive controls. The greatest increases in CTLA-4 expression were, however, seen in the CD4+ Foxp3- effector T cell population which contained 78% of all CD4+ CTLA-4+ cells in the pleural cavity. Depletion of CD25+ cells from the pleural CD4+ T cell population did not increase their Ag-specific proliferative response in vitro, suggesting that their hyporesponsive phenotype is not directly mediated by CD4+ CD25+ Treg cells. Once infection had established, killing of adult parasites could be enhanced by neutralization of CTLA-4 in vivo, but only if performed in combination with the depletion of CD25+ Treg cells. This work suggests that during filarial infection CTLA-4 coinhibition and CD4+ CD25+ Treg cells form complementary components of immune regulation that inhibit protective immunity in vivo.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Babayan, Dr Simon
Authors: Taylor, M.D., Harris, A., Babayan, S.A., Bain, O., Culshaw, A., Allen, J.E., and Maizels, R.M.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Journal of Immunology
ISSN (Online):1550-6606

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