CD40LG and rheumatoid arthritis: To establish the prevalence and significance of Aa exposure at different stages of RA development, we assayed IgM, IgA and IgG antibodies to LtxA in sera from 73 PH individuals, 567 non-RA controls, 526 pre-symptomatic individuals, 231 patients with early RA, and 170 patients with established RA.