The dendritic cell (DC) is presenting an antigen to a T cell but the T cell doesn’t recognize it. This is making the DC kind of sad.
In this case the DC is presenting the antigen on an MHC-I molecule and it is showing to a CD8 T cells. However, the T cell will recognize and respond to the antigen, only when if it is a specific antigen and it is bound to a particular MHC molecule. This process is called MHC restriction.
To learn more about antigen presentation and MHC restriction check out these links:
- Video: MHC Class I Processing
- Video: MHC Class II Processing
- Poster: Nature Immunology Antigen Processing
- Funny Comic by Pedromics: Presentation of the Antigen
- Immunobiology Book: The major histocompatibility complex and its functions
Figure 5.16 T-cell recognition of antigens is MHC restricted