GZMK and rheumatoid arthritis: For the 24 T cell subclusters analyzed in this study, the CD4+ and CD8+ cell subsets are mostly enriched in RA-immune SSL-like CD4+ Tfh and Tph cells, regulatory CD4+ T cells (Treg, T-8), CD146+ memory cells (T-11), CD8+ granzyme K/B+ memory cells (T-13), and CD8+ activated/NK-like cells (T-17) (Figure 5A).