CD4 and rheumatoid arthritis: Evaluation of the overall CD4 T cell cytokine milieu by unsupervised hierarchical clustering of flow cytometric data, led to a clear demarcation of ACPA− and ACPA+ RA patients with ACPA− demonstrating increased polyfunctionality and distinct grouping compared to ACPA+ RA patient synovial CD4 T cells (Figure 5B–D).