Individual IFNs are technically difficult to measure (23) due to their very low concentrations and presumed rapid consumption, but it seems that many of the 17 different type I IFNs, which includes 13 IFNα isoforms, IFNβ, and the three less explored members, IFNε, IFNκ, and IFNω are elevated in SLE patients, as well as in patients with Sjögren's syndrome (24, 25), systemic sclerosis (26, 27), polymyositis, dermatomyositis (28, 29), rheumatoid arthritis (30, 31), and other related diseases. Here, IFNK is linked to systemic lupus erythematosus.