IFNG and rheumatoid arthritis: On the other hand, under stimulated conditions, RA patients showed statistically significant lower levels of interferon (IFN)-γ (276.9 pg/mL, p < 0.05) and TNF-α (109.9 pg/mL, p < 0.05) when compared to HCs (1115 pg/mL and 358.9 pg/mL, respectively).