Fibrinogen-containing circulating immune complexes (ICs) are associated with anti-cyclic-citrullinated peptides (CCP) antibodies, rheumatoid factor (RF) and a disease duration of more than 10 years. Scatter plots are presented for the association of (a, b) fibrinogen ICs with IgG and IgM ICs; (c) anti-citrullinated fibrinogen antibodies with anti-CCP antibodies; (d) fibrinogen ICs with anti-CCP antibodies; (e) RF; and (f) anti-citrullinated fibrinogen. Lines were drawn to mark the negative and positive measurements of each species. (g, h) Levels of fibrinogen ICs are also plotted in RA patients with (g) more than 10 years disease duration and (h) smoking history. (i) Unsupervised hierarctical clustering  of 30 RA patients and levels of fibrinogen-circulating ICs, anti-citrullinated fibrinogen antibodies, RF and anti-CCP are presented as a heatmap. Tree dendrograms represent the statistical relatedness between patients.