ackground : Interleukin-6 (IL-6), previously known as B cell stimulatory factor 2 (BSF-2) is a multifunctional cytokine that is produced by a various cells and plays an important role in the host defence mechanism such as regulationof immune
response,
acute phase reaction and hematopoiesis. Recent investigations have demonstrated that unregulated
expression of IL-6 gene and overproducion of IL-6 were involved in the pathogenesis of
cardiac myxoma, Castleman's disease, autoimmune disease, proliferative glomerulonephritis and
certain lymphoid malignancies, especially plasmacytoma/multiple myelomas. We tried to
evaluate the regulatory effect of IL-6 on the pathogenesis of rheumatoid arthritis (RA)
which is characterized by hyperactivation of B cells, presence of various autoantibodies and
increase in acute phase proteins and platelets.
Methods : The IL-6 activity was measured by bioassay using the murine IL-6 dependent
hybridoma cell lines (MH60. BSF2), ELISA method and immunohistochemical analysis.
Results :
1) IL-6 activity was significantly elevated in synovial fluid from patients with rheumatoid
arthritis (RA, n=25) as compared with osteoarthrits (OA, n=6) and seronegative arthritis
(SNA, n=4) (p<0.05).
2) IL-6 activity was also elevated in serum from patients with RA as compared with
other disease (P<0.01).
3) High IL-6 activity and destructive changes in affected joints had a tendency to be
correlated (r=0.716).
And positive correlations between IL-6 activity and C-reactive proteins in serum
were observed in patients with RA (r=0.752).
4) Immunohistochemical analysis demondtrated that positive-staining cells were located on
the perivascular space.
Conclusion : The resulys suggest that unregulated production of IL-6 may play an
important role in the pathogenesis of RA and could explain local as well as generalized
symptoms of RA. However, it is not known whether excessive production of IL-6 is a
primary event in the disease process, or secondary consequence.
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