Objective: To elucidate the role of cytokines in the pathogenesis of familial Mediterranean fever (FMF), an inherited disease characterized by attacks of serosal membrane inflammation.
Methods: Blood samples were obtained from patients with FMF during attacks and remission. The cytokine concentrations in plasma and in supernatants from whole blood stimulated by bacterial lipopolysaccharide (LPS) were determined.
Results: There were 27 patients with FMF, of whom 8 were studied during attacks, 9 during remission and 10 during both attack and remission. FMF attacks did not affect levels of plasma tumor necrosis factor-alpha (TNF-alpha) or interleukin 1beta (IL-1beta). In contrast, compared to remission, FMF attacks were associated with significantly higher mean levels of plasma IL-6 [8.4 pg/ml, 95% confidence interval (CI) 7.8-8.9 in remission vs 59 pg/ml, CI 21.4-96.7 during attacks; p=0.0005], sTNFr p55 (1.3 ng/ml, CI 1.2-1.4, vs 1.98 ng/ml, CI 1.6-2.3; p=0.005), and sTNFr p75 (2.9 ng/ml, CI 2.5-3.3, vs 4.09 ng/ml, CI 3.2-4.9; p=0.0249). The TNF-alpha, IL-1beta, and IL-6 content in supernatants derived from LPS stimulated blood cells was not modified by the attacks of FMF. Significant lower TNF-alpha release in LPS stimulated whole blood was detected in patients who were sampled in a later stage of the attacks (r=-0.54, p=0.047).
Conclusion: Our results suggest that the cytokine network is activated during attacks of FMF. IL-6 appears to play an important role in the evolution of FMF attacks. Whether TNF-alpha or IL-1beta has a function in initiating the attacks remains to be established.