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. Author manuscript; available in PMC: 2015 Jun 1.
Published in final edited form as: Arthritis Rheumatol. 2014 Jun;66(6):1482–1491. doi: 10.1002/art.38393

Figure 2.

Figure 2

Reduction of autoantibody levels, but not serum citrulline levels, in peptidylarginine deiminase 4 (PAD4)–deficient mice with tumor necrosis factor α (TNFα)–induced arthritis. Sera from TNF+ PAD4+/+ and TNF+PAD4−/− littermates at age 5 months were subjected to multiplex assay to detect autoantibodies against individual citrullinated (Cit) and native antigens. A, Median fluorescence intensity of individual serum samples is displayed in a heatmap of antigens against which antibodies are present at higher levels in sera from TNF+PAD4+/+ mice compared to sera from TNF+PAD4−/− mice (false discovery rate <0.1% by Significance Analysis of Microarrays). B, Sera from TNF+PAD4+/+ mice (shaded bars) and TNF+PAD4−/− littermates (open bars) at age 5 months were analyzed by enzyme-linked immunosorbent assay to detect autoantibodies against citrullinated and native histone H2B and vimentin (Vim) antigens (n = 6 littermate pairs). C, Sera from TNF+PAD4+/+ and TNF+PAD4−/− littermates at age 5 months were desalted and subjected to the color development reagent (COLDER) assay to quantify citrulline. Values are the mean ± SEM. * = P < 0.05; ** = P < 0.01 by paired t-test.