Fig. 3

B cell antigen tetramer analysis in individuals with PTPN22 risk allele. a. Gating strategy for identification of citrullinated fibrinogen (cit-Fib) (pooled tetramers from four α-chain-derived Fib peptides) reactive B cells from peripheral blood mononuclear cells (PBMC). Cells were gated on forward scatter /side scatter to select for lymphocytes and removal of doublets followed by dumping of CD3⁺ CD14⁺ and CD16⁺ cells. All remaining tetramer analysis was performed on CD19⁺ CD20⁺ B cell subsets. b. Cit-Fib tetramer analysis in PBMC (frozen) from 5 patients with rheumatoid arthritis (RA), who served as a pilot cohort. CC PTPN22 risk allele non-carriers, CT risk carriers. Median difference between the two groups was not statistically significant. c. Cit-Fib tetramer analysis in PBMC (fresh) from 10 patients with RA, who served as a validation cohort. Median difference between the two groups was not statistically significant