CD40LG and rheumatoid arthritis: The rheumatoid factor IgM (of the immunoglobulin M class) is 60–80% positive in RA, but is also positive in up to 50% of non-RA patients suffering from B-lymphocytic leukaemia [7] and additional B-NHL subgroups, such as diffuse-large-B-cell lymphoma (DLBCL), as shown in relatively small cohorts of patients [8].