Israel Medical Association Journal

Background: Rheumatoid arthritis (RA) is a chronic inflammatory and destructive joint disease with the presence of autoantibodies, rheumatoid factor (RF), and anti-citrullinated protein antibodies (ACPA). The presence of RF or ACPA predicts RA severity. Data on the influence of ACPA titer on RA course are limited.

Objectives: To determine the correlation between ACPA titers at the time of RA diagnosis to RA features and severity during 3 years of follow-up.

Methods: We performed a retrospective study of RA patients treated at our institution during the years 2006–2015 with known ACPA titers at RA diagnosis who completed at least 3 years of follow-up. Patients (N=133) were divided according to ACPA titer: seronegative (< 15 U/ml, n=55), weakly positive (15–49 U/ml, n=18), moderately positive (50–300 U/ml, n=29), and strongly positive (> 300 U/ml, n=31). Patient data, including disease activity score (DAS28), bone erosion on hand and/or foot X-rays, treatments with corticosteroids and disease-modifying-anti-rheumatic drugs (DMARDs), and hospitalizations, were recorded. Chi-square and Mann-Whitney method were used for statistical analysis. P < 0.05 was considered as statistically significant.

Results: Male gender, smoking, and RF positivity correlated with ACPA positivity and higher ACPA titers. There was no correlation between ACPA titer and the variables defined as representing RA severity: higher DAS28, bone erosions, hospitalizations, need for corticosteroids, and conventional and biological DMARDs.

Conclusions: Titer of ACPA was not identified as a predictive factor for RA severity

Serum rheumatoid factors are autoantibodies of different isotypes directed against the Fc fraction of immunoglobulin G (IgG) and represent paradigmatic autoantibodies that have been largely used in clinical practice for decades. Traditionally IgG has been associated with rheumatoid arthritis and more recently included also in the classification criteria for Sjӧgren’s syndrome. Researchers have established that rheumatoid factors are positive in a variety of infectious, autoimmune, and neoplastic disorders, thus requiring a comprehensive evaluation of seropositive patients. Of note, hepatitis B and C viruses represent a crossroad that includes the high rheumatoid factor seroprevalence and chronic inflammatory disease, as well as progression to non-Hodgkin's lymphomas. Chronic antigen stimulation is the likely common ground of these processes and rheumatoid factors may represent mere bystanders or drivers of pathology. Mixed cryoglobulinemia and lymphoproliferative disease are prime examples of the deleterious effects of rheumatoid factor-B cell activity, possibly associated with hepatitis B and C. More importantly, they show a clear association in a physiological host response to infection, chronic inflammation, and the slide toward autoimmunity and malignancy. The association between hepatitis B and C infections and the appearance of serum rheumatoid factors is further supported by prevalence data, which support a coexistence of these markers in a significant proportion of cases, with viral infections being frequent causes of rheumatoid factors in patients without a rheumatic condition. We provide a comprehensive overview of the known connections between hepatitis B and C infections and rheumatoid factors.

Background: 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[1]. In addition, these alleles may also have relevance for disease outcome. Anti-CCP[2] antibody positivity has been associated with the presence of HLA-DR4 alleles in patients with RA. However, there is little information available regarding any relationship between quantitative anti-CCP production (serum anti-CCP concentrations) and the shared epitope.

Objectives: To determine the association between anti-CCP antibody production and various HLA-DRB1 alleles.

Methods: Serum anti-CCP, rheumatoid factor and C-reactive protein levels were assessed in 53 RA patients. All these patients underwent HLA-DRB1 genotyping.

Results: Of the 53 patients 33 (62%) were positive for anti-CCP antibody. We found significant correlations between anti-CCP and RF[3] positivity (chi-square = 6.717, P < 0.01), as well as between anti-CCP and HLA-DRB1*04 positivity (chi-square = 5.828, P < 0.01). There was no correlation between RF positivity and serum levels, CRP[4] serum levels and HLA-DRB1*04 positivity. When quantitatively comparing serum anti-CCP levels with shared epitope positivity, patients carrying one or two copies of HLA-DRB1*04 alleles had significantly higher anti-CCP concentrations (530.0 ± 182.6 U/ml) compared to DRB1*04-negative patients (56.8 ± 27.4 U/ml) (P < 0.01). There was no difference in serum anti-CCP antibody concentrations between patients carrying only one HLA-DRB1*01 allele but no HLA-DRB1*04 allele (12.0 ± 8.6 U/ml) in comparison to SE[5]-negative patients (76.8 ± 56.2 U/ml). Regarding non-SE HLA-DRB1 genotypes, all 6 patients (100%) carrying DRB1*15 alleles and 6 of 7 (85%) patients carrying DRB1*13 were anti-CCP positive. In addition, patients with HLA-DRB1*13 (282.5 ± 23.8 U/ml) and DRB1*15 (398.7 ± 76.2 U/ml) produced significantly more anti-CCP than did any other non-SE HLA-DRB1 subtypes (P < 0.01).

Conclusions: 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