IFI16 and rheumatoid arthritis: IFI16 protein has been found to be present in the serum of many patients with autoimmune diseases, including systemic sclerosis (SSc), systemic lupus erythematosus (SLE), desiccation syndrome (SjS), and RA.It is noteworthy that the highest serum IFI16 protein levels were found in a limited number of RA subjects (152).