Fig. 4

a Anti-PF4 immunoblot analysis using the heparin-binding fractions isolated from RA or OA patient sera. Heparin-binding fractions isolated from RA and OA patient sera using heparin-Sepharose-4B beads were subjected to anti-PF4 immunoblot analysis. PF4 bands (MW = 7800) were detected in the heparin-binding fractions from RA patients or OA patients under reducing conditions. A representative result of three independent experiments. b, c Anti-PF4 immunoblot analysis using the IgG fractions from healthy subjects (b) or RA and OA patient sera (c) using protein G sepharose-4B beads were subjected to anti-PF4 immunoblot analysis. PF4 bands (MW = 7800) were detected in the IgG fractions from RA patients under reducing conditions. Additional brood bands observed under reducing conditions are light chains generated from cleavage of the thiol-disulfide bridge of immunoglobulins. In Fig. 3c, among four patients, anti-CCP Ab plus RF were detected in two patients (RA2 and RA4). A representative result of three independent experiments. OA osteoarthritis, RA rheumatoid arthritis