Since we aimed to distinguish the myeloid cell-specific mediators of transition from immunized condition, characterized by accumulation of inflammatory innate cells, towards the onset of overt arthritis, which are altered by Fas deficiency, we analyzed the gene expression profile of CD11b+Gr-1+ cells from the synovial compartment of IMM and AIA wt and Fas −/− mice purified by FACS. Here, FAS is linked to Arthritis.