Figure 2.

Molecular mimicry and epitope spreading: hypothetical scenario for environmental triggering factors as inducers of autoimmune disease. Infection of the host by a pathogen that shares a structural similarity with a host molecule (molecular mimicry) occurs long before diagnosis. The initial epitope recognized by specific antibodies functions as an origin of intramolecular epitope spreading occurring as result of somatic hypermutations in B cells and the subsequent dynamic antibody response. Thereby, the reactivity to the initiating epitope might be lost over time leaving behind immunodominant epitopes that have nothing in common with the pathogen structure that was responsible for the initiation of the autoreactivity. Thus, at the time of diagnosis, there is no obvious link to an infection with a pathogen that mimics a host component.