Purified anti-CCP2 IgGs bind in vivo -generated epitopes in rheumatoid arthritis (RA) synovial tissue and synovial fluid (SF) cells. Immunohisto-/immunocytochemical stainings of RA synovial tissue (top panel) and RA synovial fluid cells (bottom panel) using a pool of 26 purified anti-CCP2 IgG eluate fractions from SF (left panel) or a pool of the corresponding CCP2 column IgG flow-through fractions (right panel). Magnifications: 10× (synovial tissue) and 25× (SF cells). Representative pictures from n = 3 RA patients (synovial tissue) and n = 3 RA patients (SF cells) are shown. CCP, cyclic citrullinated peptide; IgG, immunoglobulin G.