We identified a cluster of CD4+FOXP3+ Tregs (characterized by high CD4, FOXP3, PDCD1, CTLA4, TIGIT, and IL2RA expression, Figure 2—figure supplement 2A, B) that showed increased frequency in RA patients compared to OA (Figure 2—figure supplement 2C). Here, IL2RA is linked to rheumatoid arthritis.