Abstract:Objective To investigate the expression levels of chemokine 2 (CCL2) and chemokine receptor 2 (CCR2) in synovial fluid of patients with rheumatoid arthritis (RA)at acute active stage and their significance. Methods From January 2016 to January 2017, 49 RA patients were selected as acute active group(at acute active stage of RA), and 46 RA patients were selected as stable group(at stable stage of RA). At the same time, 41 patients with knee joint injury were served as control group. Enzyme-linked immunosorbent assay (ELISA)was used to detect the level of CCL2 in synovial fluid, and flow cytometry was used to measure the expression level of CCR2 which was presented by the proportion of CCR2+T cells in CD4⁺T cells.? Results Compared with control group and stable group, the level of CCL2 and the percentage of CCR2 in CD4⁺ T cells significantly increased in acute active group(P<0.05, P<0.01). There was no significant difference in CCR2 expression on CD4⁺ T cells between control group and stable group (P>0.05). In acute active group, the level of CCL2 was significant positive correlation with the expression of CCR2 (r=0. 547, P<0.05); the level of CCL2 and CCR2 expression level on CD4⁺T cells were significant positive correlation with Lansbury index, C reactive protein, rheumatoid factor, erythrocyte sedimentation rate, and disease activity score with 28 joint(all P<0.05).? Conclusion Level of CCL2 and expression of CCR2 on CD4⁺ T cells increase significantly in RA patients and is positively correlated between them. They are also positively correlated with the clinical activity indexes of acute active period, which could be used as a reference index to evaluate the activity of rheumatoid arthritis.