TNF and rheumatoid arthritis: Similarly, the level of the cytokines: IL-8 (Fig. 2B), RANTES (Fig. 2C), IL-6 (Fig. 2D) and TNFα (Fig. 2E) were significantly elevated, suggesting that the up-regulation of TREM1 correlates with activation of PMNs in RA patient specimens and demonstrating that TREM1 increased expression is also linked to an increase in its activity.