RNASET2 and rheumatoid arthritis: To understand the potential relationship between RNASET2 synovial expression and the histopathological features of human synovial RA tissue, we performed IHC staining and RNASET2 immunoreactivity analysis of the synovial biopsy of a RA patient with active disease, characterized by a strong inflammatory infiltrate (Fig. 6A, panel a).