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Researchers compare CCP profile of patients with JIA vs RA
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Among patients with rheumatoid arthritis and patients with a polyarticular subtype of juvenile idiopathic arthritis, researchers at University College London compared profiles of antibodies to cyclic citrullinated peptide profiles.
“[This] study has demonstrated the novel finding that adolescent [rheumatoid factor-positive polyarticular juvenile idiopathic arthritis] pJIA (RF+ve) patients are distinct in their anti-[cyclic citrullinated protein] CCP antibody phenotype from other JIA clinical patterns and age/sex matched healthy controls; but are comparable to adult RF-positive patients in their levels of IgG anti-CCP and shared expression of the same inherently autoreactive 9G4 idiotype,” Yiannis Ioannou, PhD, at the Arthritis Research UK Centre for Adolescent Rheumatology at University College London, and colleagues wrote. “However, it was found that the adult group had significantly higher levels of IgA and IgM anti-CCPs than the adolescent group, suggesting that further investigation is needed to fully elucidate the extent to which these two conditions may be seen as one.”
In the study, there were 88 patients with pJIA; 29 patients with enthesitis-related arthritis (ERA); 38 patients with extended oligoarthritis (EOA); 31 adolescent controls; 35 patients with RA; and 30 adult controls. Of the patients with pJIA who were RF-negative, 4.6% were also IgG anti–CCP-positive. In addition, 87% of patients with pJIA were RF-positive; 85.7% of patients with RA and one patient with EOA had sera that contained IgG anti-CCP. Overall, investigators found lower levels of IgA and IgM anti-CCP in the adolescent cohort.
In the pJIA group, 9G4-CCP levels were greater in the subgroup that was RF-positive compared with the RF-negative group. Median level of 9G4-CCP in RF-positive pJIA was no different from patients with RA. In addition, 9G4 on serum total IgM was greater in patients with pJIA who were RF-positive vs. adolescent groups, but was similar to adult patients with RA who were RF-positive.
“In healthy individuals, 9G4+B cells comprised 5% to 10% of peripheral blood pool, but serum immunoglobulins utilizing VH4-34 are disproportionately low,” the researchers wrote. “The idiotope recognized by 9G4 was detected on anti-CCP antibodies in greater than 80% of pJIA(RF+ve) patients. VH4-34 usage by anti-CCP in both JIA and RA patients suggest elicitation of these autoantibodies through shared pathogenic B cell selection processes.” – by Will Offit
Disclosure: The researchers report no relevant financial disclosures.
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