CD4 and rheumatoid arthritis: The median proportion of IL-17-producing CD4 T cells in SFMC (n = 14) (1.81% (0.81 to 3.97)) was significantly (P = 0.04) greater than in PBMC (n = 44) (1.08% (0.60 to 1.64)) from RA patients, and increased compared with PBMC (n = 13) (0.84% (0.58 to 1.40)) from healthy controls (Figure 1A, 1B).