Figure 1.

Some of the mechanisms proposed for the role of DR in RA. (a) DR molecules provides peptides for binding to other MHC molecules which will trigger T cells that regulate pahogenic T cells. (b) DR- self peptide complexes select the T cell repertoire that may have a regulatory impact on the activation of pathogenic T cells. (c) DR molecules bind self peptides, which may or may not be derived from joint tissue, that trigger pathogenic T cells. (d) Another possibility is that DR molecules binds peptides derived from infectious agents that may persist in the joints or give rise to a self cross-reactive T cells. Subsequently the activated T cells could induce, modulate or regulate the erosive destruction of the joints.