Studies on thrombocytes in patients with rheumatoid arthritis Part 2. Platelet specific protein in patients with rheumatoid arthritis.

Plasma β-thromboglobulin (β-TG) concentration and platelet factor 4 (PF(4)) activity were examined and related to parameters of inflammation in patients with rheumatoid arthritis (RA). In 42 RA patients, the β-TG concentration assessed by radioimmunoassay (β-TG RIA KIT Amersham) was significantly higher than that of 17 normal controls (p<0.002). The β-TG concentration correlated with the platelet count (γ=0.68, p<0.01) and erythrocyte sedimentation rate (γ=0.32, p<0.005). Plasma PF(4) activity, tested by heparin neutralizing activity, was significantly higher than that of 17 normal controls (p<0.001). In the strongly positive CRP group (CRP 3(+) or more) PF(4) activity was significantly higher than in the weakly positive CRP group (less than CRP 2(+)) (p<0.05). No correlation between PF(4) activity and other parameters such as the platelet count, erythrocyte sedimentation rate, fibrinogen, antithrombin Ⅲ, or FDP was demonstrated. These results suggest that accerelated platelet functions were present in patients with clinically active RA.