CD4 and rheumatoid arthritis: IL-22 and IL-17 double positive CD4 T cells (Figure 3A) were hardly detectable in PBMC (0.07% (0.02 to 0.30)), or SFMC (0.16% (0.04 to 0.35)) of RA patients and PBMC (0.16% (0.07 to 0.21)) of healthy controls.