Figure 6.

Cross-reactivity of autoantibodies to citrullinated F-actin capping protein α-1 subunit (CapZα-1). To investigate cross-reactivity to other synovial proteins, the autoantibodies purified with citrullinated CapZα-1 (lane 1), control human immunoglobulin G (lane 2), polyclonal anti-CapZα-1 antibodies (lane 3), and rheumatoid arthritis serum samples (lane 4) were reacted with synovial tissue proteins separated by SDS-PAGE. The purified autoantibodies cross-reacted with five protein bands (arrows). Three bands (white arrows) were not reacted with polyclonal anti-CapZα-1 antibodies. On the other hand, two bands (black arrows) were reacted with polyclonal anti-CapZα-1.