Compared with normal samples, RA samples had distinctly higher levels of Activated.CD4.T.cell, Activated.CD8.T.cell, Activated.dendritic.cell, Immature.dendritic.cell, Gamma.delta.T.cell, Eosinophil, CD56dim.natural.killer.cell, MDSC, Macrophage, Mast.cell, Neutrophil, Regulatory.T.cell, Type.17.T.helper.cell, Type.2.T.helper.cell, Memory.B.cell, Central.memory.CD4.T.cell. The gene discussed is CD8A; the disease is rheumatoid arthritis.