IL17A and rheumatoid arthritis: Higher levels of IL-21 were produced by RA PBMC after 2 and 18 h with respect to Control; higher levels of IL-23 and IL-6 were produced by PBMC from RA patients after 18 and 72 h as compared to Control, while a significant increase of IL-22 and IL-17A was evidenced only after 72 h (Fig. 6C).