IFNA1 and systemic lupus erythematosus: CSF IFN activity was assessed in active j-NPSLE, inactive j-NPSLE, and j-SLE controls in 18, 9, and 8 patients, respectively, as negative in 83% (n = 15/18) of active j-NPSLE (negative in all inactive j-NPSLE and j-SLE controls) and not statistically different (active vs inactive j-NPSLE p = 0.4554 and active j-NPSLE vs j-SLE controls p = 0.5292, data not shown).