Enhanced Fcgamma receptor I, alphaMbeta2 integrin receptor expression by monocytes and neutrophils in rheumatoid
Andreia Bunescu1, Peter Seideman, Rodica Lenkei
1Department of Clinical Chemistry, Capio Diagnostik, St. Göran's Hospital, 11281 Stockholm, Sweden. Andreia.Bunescu@capio.se
Objective:
To investigate platelet and leukocyte activation and interaction in patients with rheumatoid arthritis (RA) and the effect of methotrexate (MTX) or anti-tumor necrosis factor-a (TNF-a) treatment on these variables.
Methods:
Four-color flow cytometry analysis was performed for quantitative measurement of platelet (P-selectin, PAC-1) and leukocyte (CD11b, CD64) activation markers and estimation of percentage of leukocyte-platelet complexes in whole blood in 20 patients with RA before and after 6 weeks of therapy and in 20 controls. In addition, measures of soluble P-selectin (sP-selectin), beta-thromboglobulin, fibrinogen, prothrombin fragment 1+2, D-dimer, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), interleukin 6 (IL-6), and TNF-a and tender and swollen joint counts were carried out.
Results:
Before therapy, PAC-1 binding, expression of CD11b and CD64 on monocytes and neutrophils, circulating levels of monocyte (CD11b+ or CD64+)-platelet complexes, monocyte-PAC-1+ platelet complexes, CRP, ESR, IL-6, TNF-a, fibrinogen, D-dimer and sP-selectin were significantly higher in RA patients compared to controls. The anti-TNF-a therapy significantly reduced levels of monocyte-PAC-1+ platelet complexes, sP-selectin, CRP, ESR, IL-6, TNF-a, fibrinogen, and D-dimer and tender and swollen joint counts. CD64 expression on monocytes was significantly decreased by MTX therapy. PAC-1 binding was not inhibited by MTX or anti-TNF-a.
Conclusion:
Increased platelet and leukocyte activation and increased formation of leukocyte-platelet complexes in patients with RA suggest a status of simultaneous activation of the immune and hemostatic systems.
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