CD2 and rheumatoid arthritis: We observed enrichment of 6 genes including GZMB, KLRB1, CD2, CD3D, CD8A, and GZMK in all 8 algorithms, where CD2 (Raychaudhuri et al., 2009), CD8A (Carvalheiro et al., 2015; Souto-Carneiro et al., 2020), and GZMB (Bao et al., 2018) had already been reported as important genes involved in the progression of RA (Figure 4E).