Objective: The aim of the study was to evaluate the pattern of the lymphoid organization in the synovial tissue of patients affected with juvenile idiopathic arthritis (JIA).
Methods: A total of 40 JIA patients who underwent synoviectomy or synovial biopsies were enrolled. The mean age at surgery was 15.1 yrs (range 6-30 yrs) and the mean disease duration was 6.7 yrs (range 3 months to 22.2 yrs). Tissue specimens were grouped according to the following criteria: (i) diffuse perivascular infiltrate without lymphoid organization, (ii) T cell-B cell aggregates with or without germinal centre reaction.
Results: Synovial tissues from 12 JIA patients did not show any sign of lymphoid organization, whereas 28 patients displayed a variable number of T-B cell aggregates. Typical features consistent with a germinal centre reaction were present in two JIA patients only. Lymphoid organization in JIA patients did not correlate with the duration and severity of the disease or with the degree of synovial inflammation, but did positively correlate with the presence of anti-nuclear antibodies. Moreover, a diffuse lymphocyte infiltration was significantly related to the presence of an acute phase of inflammation and the presence of lymphoid aggregates correlated with the degree of plasma cells infiltration.
Conclusions: Lymphoid neogenesis in JIA represents a phase in the immunopathological process that characterize the development of inflammatory synovitis. It is not related to disease activity or severity, but appears to be more frequent in patients with circulating anti-nuclear antibodies.