Isr Med Assoc J
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The presence of anti-cyclic citrullinated peptide autoantibody is highly specific for rheumatoid arthritis. Certain HLA-DR4 (HLA-DRB1*04) alleles, also known as the "shared epitope," are associated with increased susceptibility to RA. In addition, these alleles may also have relevance for disease outcome. Anti-CCP antibody positivity has been associated with the presence of HLA-DR4 alleles in patients with RA. However, there is little information regarding a relationship between quantitative anti-CCP production (serum anti-CCP concentrations) and the shared epitope. ⋯ There is significant association between anti-CCP and RF, as well as between anti-CCP and SE positivity in RA. In addition, the presence of one or two copies of HLA-DRB1*04 alleles has been associated with higher serum anti-CCP antibody levels. Thus, patients carrying HLA-DRB1*04 alleles exhibited an overall tenfold increase in serum anti-CCP antibody levels in comparison to HLA-DRB1*04-negative subjects. Increased anti-CCP production may also be associated with other non-SE HLA-DRB1 genotypes, such as DRB1*13 or DRB1*15. In reports by other investigators, both anti-CCP concentrations and SE positivity were related to more rapid disease progression and unfavorable outcome.