BACTERIAL VIRULENCE ANTIGENS AND THE PATHOGENESIS OF AUTOIMMUNE THYROID-DISEASES (AITD)

There is now substantial evidence that autoimmune thyroid diseases (AI TD) coincide with a subclinical persisting infection with Yersinia ent erocolitica (YE) which manifests through humoral and cellular immune r eactions against YE at the onset of AITD. The humoral and cellular cro ssreactivities of YE with thyroid autoantigens are exclusively directe d against conformational epitopes of YE membrane associated antigens a nd of YE plasmid encoded virulence proteins (YOPs). Especially, the ou ter membrane domain of the TSH-Receptor (THSR) appears to have conform ational homologies with YE antigens. Immunological-and molecular findi ngs, however, do not allow definite conclusions about a potential role of YE-infection in AITD, although the evidence is suggestive. Recent investigations on the effect of YE-superantigen (Sag) on T-cells from patients with AITD as well as AITD like manifestations in YE immunized mice and rats may yield more conclusive information about the role of YE infection in the pathogenesis of AITD.