IFNA1 and systemic lupus erythematosus: To search for neutrophil autoantigens linked to IFN activation in SLE, we initially identified in vivo–activated cells by IFN through the study of protein expression of the IFN-induced protein with tetratricopeptide repeats 3 (IFIT3) — as marker of IFN-induced activation (21) — in freshly isolated peripheral blood neutrophils and peripheral blood mononuclear cells (PBMCs) from consecutive patients with SLE (Figure 1A).