Table 1.

The specificity information of different monoclonal antibodies in this study

Antibodies	Origin	Classification	Isotype	Specificity
E4	Chimeric antibody isolated from RA patients	Promiscuous	hIgG1	Reactive with several citrullinated peptides, including citrullinated F4 derived from COL2 [14]
ACC4	Triple-helical citrullinated C1 epitope immunized mice	Private specific	hIgG1	Specific for the alpha chain of citrullinated C1 epitope on COL2 [22, 23]
ACC1	Triple-helical citrullinated C1 epitope immunized mice	Private cross-reactive	hIgG1	Reactive with citrullinated C1 epitope on COL2 but also cross-reactive with several epitopes on triple-helical COL2 [22, 23]
M2139	COL2 immunized mice	Joint reactive	hIgG1	Specific for the J1 epitope on triple-helical COL2 [37]