Yersinia arthritis in the Midlands: clinical and immunological features in ten cases during 1980-1983.

Ten cases of Yersinia arthritis, nine of whom were known to be B27 positive were seen in the Midlands between 1980 and 1983. Diagnostic difficulty arose in four cases owing to unusual form of presentation or course. Two of the cases studied during the acute phase showed a marked degree of lymphocyte transformation in the presence of Y. enterocolitica 0:3 in a dose-related form. This does not lend support to the concept of molecular mimicry between the bacterial antigen and the B27 gene product since this would be more likely to result in a diminished response.