Abstract: Objective To investigate the role of interleukin-6(IL-6), interleukin-8(IL-8) and tumor necrosis factor-α(TNF-α) in the pathogenesis of secondary syphilis, and their relationship with RPR titers and clinical manifestations in secondary syphilis. Methods The serum IL-6, IL-8 and TNF-α were tested by ELISA. RPR titers of the patients were determined simultaneously. Histopathology was performed if skin lesions were present. Results Thirty three cases of secondary syphilis were studied. The average levels of serum IL-6, IL-8 and TNF-α were 78.7±82.5 pg/mL, 171.9±117.9 pg/mL and 115.7±67.9 pg/mL, respectively, in syphilis group, which were significantly higher in comparison with those in controls (P<0.001). The levels of IL-6, IL-8 and TNF-α were significantly higher in 5 patients with psoriasiform skin lesions and more than 1:64 of RPR titers which were higher than those in patients without skin lesions (P<0.01). The levels of IL-6, IL-8 and TNF-α were also much higher in 3 cases with Jarisch Herxheimer reaction than those in patients without such reaction, which were reduced to the normal range at the end of three week treatment. Conclusions Elevated serum levels of IL-6, IL-8 and TNF-α are closely associated with secondary syphilis. These cytokines are much higher in the patients with psoriasiform skin lesions and in the patients developed Jarisch Herxheimer reaction.

Key words: Interleukin 8, Tumor necrosis factor, Syphilis, Interleukin 6