IFNA1 and arthritic joint disease: ,17,18,19,20,21 In contrast, features linked to systemic disease activity previously attributed to IFN-I (such as arthritis, nephritis, and low complement)49,52 were associated with increased activity levels of IFN-I + IFN-II + IFN-III, indicating a synergistic effect of the three IFN families in this severe disease subset.