S100A12 and rheumatoid arthritis: Based on the greater infiltration with PMCs in SpA than in RA, and a recent report on the granulocyte calcium-binding protein S100A12 in PsA [10], we assessed the expression of S100A12 in synovium of patients with PsA (n = 8), nonpsoriatic SpA (n = 12) and RA (n = 20; patient cohort 3; Table 3).