TNF and rheumatoid arthritis: In RA synoviocytes, both the combination of IL-17 and TNF-α and 3.6 ppm of Zn induced the highest level of IL-6, with Zn amplifying the effect of the added cytokines (106.4 ± 15.65 ng/ml, with cytokines only vs. 237.4 ± 35.58 ng/ml with both cytokines and Zn, p<0.01).