ANALYSIS OF SUBCLASSES OF RHEUMATOID FACTORS (RF) AND ANTIBODIES AGAINST OXIDIZED LOW DENSITY LIPOPROTEIN (ANTI-OXLDL) IN RHEUMATOID ARTHRITIS (RA) PATIENTS

Background: The presence of circulating RF can be used as prognostic marker for RA. However more than 20% of patients with severe RA show absence of this marker. We have previously shown that the presence of oxLDL circulating and in the synovial fluid of the affected joint are well correlated to the disease activity in RA (1).Objectives: In here we have analyzed the presence of subclasses of RF (i.e. IgG, IgM and IgA) and antibodies against oxidized LDL and made a crosswise comparison to elucidate their intra- and inter-relationship in a cohort of 47 rheumatoid arthritis patients.Methods: Antibodies against oxLDL or antibodies anti-apoB epitope derived from oxLDL, called D peptide (apoB-D) were measured in mouse plasma by ELISA. Anti-oxLDL antibodies was measured using highly oxLDL (20umCu, 18 hrs) in an ELISA assay.Subclasses IgG, IgM and IgA of RF were measured using a commercial ELISA kit (Hycor, Scotland, UK) according to the method provided by the manufacturer.C-reactive protein (CRP) and serum amyloid "A" protein (SAA) were measured in a nephelometric automated system (BN-II, Dade-Behring). Erythrocyte sedimentation rate (ESR) was obtained by the automated method Sedysistem (Becton - Dickinson).47 patients that meet the 1987 American College of Rheumatology (ACR) Criteria for Rheumatoid Arthritis were selected from the Rheumatology Service of FMUSP. Two relevant instruments of clinical state assessment were applied to each patient: Health Assessment Questionnaire (HAQ) and Disease Activity Score (DAS). Both instruments are previously validated in clinical trials.Results: We found a good correlation between IgM-RF and IgG-RF. No correlation was found between IgM-RF, IgG-RF and IgA-RF.A good correlation was found between anti-oxLDL and anti-Apo B-D.No correlation was found between antibodies against oxLDL and any disease activity marker (CRP, ESR, SAA or the DAS index) in these patients.No correlation was found between RF IgG, IgM or IgA and the HAQ score.When the results of HAQ score are separated in three groups of values (<1, 1-2 and >2) we found significativelly higher values of anti-oxLDL in the patients of the first group (HAQ < 1).No correlation was found between the presence of neither of the RFs and antibodies against oxLDL.Conclusion: Since that low HAQ scores could be associated with a good health statement in RA and ultimately with a good prognosis, the occurrence of higher concentrations of anti-oxLDL in patients with low HAQ could indicate that these antibodies are associated with a good general prognosis in RA. Although, this supposition should be confirmed in larger studies that includes x-ray analysis and prospectively approaches.The data suggests that both RF and anti-oxLDL can be used as independent markers in RA.1. Arthritis and Rheumatism 39(9): 1013, Suppl. S, Sep1996Citation: , volume , supplement , year 2003, page Session: Rheumatoid arthritis – Clinical aspects