In an early study, a decrease of CD4-CD8- (mostly γδ T cells) in peripheral blood (PB) of RA patients relative to healthy controls (HC) was noted (1.38 ± 1.08% vs. 3.23 ± 2.12%, p < 0.05], whereas these cells were increased in synovial fluid (SF) of patients [18]. Here, CD4 is linked to rheumatoid arthritis.