IFNG and rheumatoid arthritis: However, there was no significant difference in the titers of anti-IFN-γ IgG (median 12.69 ng/mL, IQR 10.46–17.35 ng/mL versus median 13.83 ng/mL, IQR 10.46–17.96 ng/mL, Figure 1A), or plasma levels of IFN-γ (median, 4.32 pg/mL, IQR 3.69–6.42 pg/mL versus 4.15 pg/mL, IQR 3.58–5.36 pg/mL, p = 0.56, Figure 1B) between RA patients with and without new-onset HZ.