Figures & data
Figure 1. Upregulation of indoleamine 2,3-dioxygenase expression is an early event in antigen-presenting cells, since it is induced by pro-inflammatory signals. Indoleamine 2,3-dioxygenase (IDO) protein is processed and IDO-derived peptides are presented on the cell surface of antigen-presenting cells (APCs) by class II HLA molecules, from where they are recognized by CD4+ T cells. The release of pro-inflammatory cytokines by CD4+ IDO-specific T cells may be important as a counter-response to IDO-induced immunosuppression. These CD4+ T cells may indeed help overcoming the immunosuppressive effects of IDO in the early phases of inflammatory responses. Moreover, IDO-specific CD4+ T cells may promote CD8+ cytotoxic T-cell responses, including anti-CMV and anti-IDO responses. IDO-specific CD8+ T cells may further boost T-cell immunity by eliminating IDO+ suppressive cells, for instance by releasing granzyme B (GrB) and perforins.
