Western blotting of circulating tenascin-C (TNC) in rheumatoid arthritis (RA) patients. (A) In baseline samples from RA patients one predominant TNC band of 320 kDa was observed (n = 18). Corresponding TNC levels detected in the same samples by ELISA are shown in pg/ml under the blot. Low levels of TNC were detected in healthy control plasma (N). rhTNC, 0.05 μg human recombinant TNC. (B) In addition to the major band detected at 320 kDa, bands of MW 219, 201, 190 and 156 kDa were present in the plasma of some RA patients upon western blotting with anti-TNC antibodies (TNC). Ponceau S staining of the same membrane shows equivalent protein loading for each RA sample.