Objective. Interleukin-10 (IL-10) is a potent stimulator of B lymphocytes in vitro. In vivo dysregulation of IL-10 gene expression was therefore analyzed in patients with rheumatoid arthritis (RA), primary Sjögren's syndrome (SS), and systemic lupus erythematosus (SLE).
Methods. Spontaneous production of IL-10 by peripheral blood mononuclear cells was measured using reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay in untreated patients with either RA (n = 10), SS (n = 10), or SLE (n = 10), and in 15 normal control subjects.
Results. IL-10 production was dramatically higher in RA, SS, and SLE patients than in controls. In each group, both B lymphocytes and monocytes, but not T lymphocytes, produced IL-10.
Conclusion. IL-10 production is increased in RA, SS, and SLE. It may play a role in B lymphocyte hyperactivity and in the development of autoimmunity.