Although the frequencies of total cTfh or cTfh subsets were similar between patients with SLE and HCs, the percentage of ICOS+PD-1+ cells was approximately 2-fold higher in total cTfh cells (Figure 1D) and across all cTfh subsets (Figure 1E) in patients with SLE compared with HCs. Here, PDCD1 is linked to systemic lupus erythematosus.