CD8A and rheumatoid arthritis: This was further elucidated by Hussein et al., who counted the CD4+ and CD8+ T-cell subsets and measured levels of some cytokines (TNF-α, IL1-β, IL-10, and IL-17) and a soluble intercellular adhesion molecule-1 (sICAM-1) in the sera and synovial fluids of RA and OA patients [33].