Likewise, SEB-reactive T cells from patients with RA and patients with SpA had higher expression levels of the anergy marker CTLA-4 (p < 0.05) (Fig. 2b, upper panel), whereas PD-1 expression was significantly higher in patients with SpA only (p < 0.05) (Fig. 2b, middle panel). Here, CTLA4 is linked to rheumatoid arthritis.