Figure 1.

(A) HSPs can bind antigenic peptides either extracellularly (I) or intracellularly (II). Subsequently, the HSP-antigen complex reaches the endoplasmic reticulum, where the loading of the major histocompatibility complex (MHC) occurs. Finally, the MHC-antigen complex is transported to the cell membrane, where the antigen is presented to the T-cell. (B) HSPs as antigens are presented by antigen presenting cells to T-cells. Afterwards, primed T-cells become effector cells. Subsequently, these effector cells normally recognize foreign HSPs on the surface of foreign tissue and induce determination of it. However, when T-cells are primed by endogenous HSPs, which are normally used for chaperone or anti-apoptotic activities, these T-cells can cross-react and destroy endogenous tissue.