Proposed 4-stage model for mechanism of T-cell suppression by imDCs. (1) Cognate TCR signaling: On recognition and binding of a CD8⁺ T cells to imDCs, LCK is activated, leading to fast-forming adhesion interactions mediated by TCR/MHC class I. (2) Activation: these interactions lead to the establishment of an immune synapse and to secretion of TLR7/8 and TREM-1 ligand(s) from CD8⁺ T cells, which activate the tyrosine kinase receptors TREM-1 and TLR7/8 on the imDC cell surface and in imDC granules, respectively. (3) Degranulation: receptor activation leads to polarization toward the contact area of imDC granules containing perforin and granzyme A. Subsequently, the imDCs discharge their lethal cargo. (4) Perforin-mediated deletion: This leads to rapid cell lysis of the CD8⁺ T cell.