IL1B and systemic lupus erythematosus: The analysis carried out on the group of patients with serositis, suffering from pathologies other than SLE and FMF, showed that P2X7R was more active in these subjects respect to SLE patients, as evidenced by increased IL-1β in both plasma and supernatants of macrophages after stimulation with pure agonist BzATP (Supplementary Figures 1A, 2D) and augmented BzATP Δ[Ca2+]I increase (Supplementary Figure 4).