M. Wuorela et al., YERSINIA-ENTEROCOLITICA SEROTYPE O-3 ALTERS THE EXPRESSION OF SEROLOGIC HLA-B27 EPITOPES ON HUMAN MONOCYTES, Infection and immunity, 65(6), 1997, pp. 2060-2066
The expression of serologic HLA-B27 epitopes on leukocytes of patients
with reactive arthritis or ankylosing spondylitis has been shown to b
e modified in the course of the disease. The purpose of this work was
to study whether phagocytosis of arthritis-triggering microbes in vitr
o alters the expression of HLA-B27 molecules on human antigen-presenti
ng cells and to characterize the underlying mechanisms. Human monocyte
s and HLA-B27- or HLA-A2-transfected human U-937 cells were exposed to
Yersinia enterocolitica serotype 0:3. The expression of different epi
topes of HLA-B27 was monitored by using immunofluorescence, and their
synthesis was determined by quantitative immunoprecipitation. Our resu
lts show that phagocytosis of Y. enterocoalitica serotype 0:3 changed
the expression of serological HLA-B27 epitopes. This was due to the re
duced synthesis of HLA-B27 molecules. The expression of especially the
epitopes which depend on the presence of peptides in the antigen-bind
ing groove was changed. The expression of the ME1 epitope, which has b
een shown to be important for- T-cell recognition in patients with rea
ctive arthritis, was decreased. Down-regulation of epitopes important
for the T-cell recognition may impair the elimination of arthritis-tri
ggering microbes and lead to persistent infection. In addition, Y. ent
erocolitica serotype 0:3 seemed to alter the repertoire of peptides pr
esented by the HLA-B27 molecules on human monocytes. This may have a r
ole in the pathogenesis of reactive arthritis via an autoimmune mechan
ism.