Comparison of the specificity of rheumatoid factor detected by latex fixation with that of regulatory rheumatoid factor

Regulatory and other rheumatoid factors in rheumatoid arthritis patients with active disease or in remission

Background

Previously, we identified a regulatory rheumatoid factor (regRF), the production of which provides rats with resistance to collagen‐induced arthritis (CIA). Immunization with conformers of IgG Fc fragments carrying epitopes specific to regRF reduces symptoms of CIA. The aim of this study was to determine whether there is a link between regRF levels and rheumatoid arthritis (RA) activity in humans in order to assess the potential of regRF as a therapeutic biotarget in RA. The variability of rheumatoid factor (RF) specificities present in the blood of RA patients was also studied.

Methods

The regRF were studied in RA patients with active disease and in remission. Variability in the specificities of RF associated with RA was studied by concurrent inhibition of RF latex fixation by variants of modified IgG.

Results

Patients in remission had regRF levels higher than in healthy subjects. The regRF in remission was characterized by tight binding to its antigen, as in healthy subjects. The regRF levels in patients with active RA varied dramatically, and regRF binding to its antigen was weak. The exacerbation of Still's disease coincided with low regRF levels and affinity, while an improvement in patient condition was associated with an increase in regRF levels and affinity. The RF specific to RA, which was detected by the RF latex‐fixation method, was a nonhomogeneous population of antibodies that included RF to lyophilized IgG, to IgG immobilized on polystyrene, and to rabbit IgG.

Conclusion

Stimulating regRF production might enable improved RA therapy.

Metabolic syndrome in rheumatoid arthritis patients: Relationship among its clinical components

BACKGROUND

Metabolic syndrome (MetS) prevalence in rheumatoid arthritis (RA) patients is known to vary considerably across the world. This study aimed to determine the prevalence of MetS in RA patients from western Mexico and to analyze the interrelation of the MetS components with the clinical variables of RA.

METHODS

This case-control study included 216 RA patients and 260 control subjects (CS). MetS prevalence was determined according to the NCEP/ATP III and the Latin American Consensus of the Latin American Diabetes Association (ALAD) criteria.

RESULTS

MetS was observed in 30.6% RA patients and 33.3% of controls (p > 0.05) according to NCEP/ATP III and 28.7% in RA patients and 31.1% for controls using ALAD criteria. Total cholesterol, LDL-C, and Castelli's I-II indexes were lower in RA (p < 0.001) than in CS. The RA patients with MetS had more swollen joints than those without MetS (p = 0.018). In RA patients with MetS, DAS-28 score correlated with smoking index (rho = 0.4601, p = 0.0004) and VLDL-C (rho = 0.3108, p = 0.0056); similarly, rheumatoid factor (RF) correlated with age (rho = 0.2031, p = 0.0027), smoking index (rho = 0.3404, p < 0.0001), triglycerides (rho = 0.1958, p = 0.0039), and VLDL-C (rho = 0.1761, p = 0.0162).

CONCLUSIONS

The MetS prevalence in RA patients from western Mexico is not higher than controls; however, in RA patients with MetS, some inflammatory markers are associated with MetS components; thus, the control of MetS in RA could be beneficial to regulate disease activity.