Further, Kuhn and colleagues showed that a monoclonal antibody specific for citrullinated fibrinogen exacerbated tissue injury in rodent models of arthritis [14], although it remains possible that this non-affinity matured IgM antibody might cross-react with a native cartilage component as described for anti-citrulline IgG responses in RA [15]. This evidence concerns the gene CD40LG and arthritic joint disease.