ILC3 produce IL-17 and IL-22, promote Th17 differentiation, drive local inflammation and correlate with clinical disease activity (91, 92)LTi cells reduced in RA lymph nodes; frequency correlates with VCAM-1 expression on endothelial cells; contribute to lymphoid tissue maintenance and stromal cell–ILC interactions (86). Here, CCL27 is linked to rheumatoid arthritis.