BRIEF REPORT The significance of platelet activation in rheumatoid arthritis Feng Wang & Nian-Song Wang & Chun-Gen Yan & Jun-Hui Li & Ling-Quan Tang Received: 17 June 2005 / Revised: 14 July 2005 / Accepted: 14 July 2005 / Published online: 6 February 2007 # Clinical Rheumatology 2007 Abstract We evaluated the significance of platelet activa- tion in patients with rheumatoid arthritis (RA). The expression of CD62P and CD63 by platelets was deter- mined using flow cytometry in 18 active RA patients, 10 remission RA and 15 normal controls. Meanwhile, the erythrocyte sedimentation rate (ESR) and C-reactive protein was also determined in all groups. The expression of CD62P in active RA patients (11.88±2.47%) was signifi- cantly higher than that in remission RA group (2.85± 1.60%; P <0.01) and control group (2.78±1.04%; P <0.01). The expression of CD63 in active RA patients (9.90± 3.02%) was significantly higher than that in remission RA group (4.11±2.00%; P <0.01) and control group (4.13± 1.85%; P <0.01). The level of CRP (54.33±23.35 mg/l) and ESR (86.06±33.67 mm/h) in active RA patients was higher than that in remission RA group (2.55±1.01 mg/l, 14.70± 4.57 mm/h; P <0.01 for both) and normal control group (3.21±2.18 mg/l, 12.25±5.05 mm/h; P <0.01 for both). There was a positive correlation between CD62P and ESR (r =0.5224, P <0.01) and also a positive correlation between CD62P and CRP (r =0.7048, P <0.01) as well as between CD63 and ESR (r =0.4476, P <0.05) but no correlation between CD63 and CRP. Platelet activation may be a sign of RA exacerbation. Keywords C-reactive protein . Platelet activation . Rheumatoid arthritis Introduction Rheumatoid arthritis (RA) is a chronic systemic inflamma- tory disease of unknown cause, which primarily affects the peripheral joints in a symmetric pattern. Patients with RA may present constitutional symptoms such as fatigue, malaise, and morning stiffness [1–3]. Extra-articular involvements of the skin, heart, lungs, and eyes can be significant. RA can result in joint destruction and thus often leads to considerable morbidity and mortality. It is believed that an RA patient may present an increasing account of platelets during active stages and that will decline in number with the remission of the inflammation [4–6]. But the activation status of the platelets is unknown. In our study, the expression of CD62P and CD63 by platelets was determined using flow cytometry to evaluate the relation between activation of platelets and the progression of RA. Materials and methods Diagnosis criteria The American College of Rheumatology developed the following criteria for the classification of RA: morning stiffness, arthritis of three or more joint areas, arthritis of hand joints of at least one area swollen (in a wrist, metacarpophalangeal, or proximal interphalangeal joint), Clin Rheumatol (2007) 26:768–771 DOI 10.1007/s10067-007-0550-0 F. Wang (*) : N.-S. Wang : J.-H. Li : L.-Q. Tang Department of Nephrology and Rheumatology, the Sixth Hospital Affiliated to Shanghai Jiaotong University, 600 Yishan Road, Shanghai 200233, China e-mail: zyzwq1030@sohu.com C.-G. Yan Department of Internal Medicine, the Hospital Affiliated to Medical College, Shaoxing College of Arts and Science, 260 Chang’an Street, Shaoxing 312000, China