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What is the percentage of patients with RA who test positive for RF over the course of their disease?
What is the significance of the presence of RF in patients with RA?
What is the frequency of positive results for ANA assays in patients with RA?
What is the significance of ACPA-positive patients?
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What is the sensitivity and specificity of anti-CCP assays compared to RF assays?
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What is the significance of the presence of both anti-CCP antibodies and RF in patients with RA?
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What is the significance of the presence of anti-CCP antibodies in patients with RA?
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Which of the following laboratory studies is NOT a marker of inflammation?
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What is thrombocytosis associated with in patients with RA?
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What percentage of healthy people may have RF present?
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Study Notes
Rheumatoid Arthritis (RA)
- RA is an autoimmune, systemic, symmetrical, chronic inflammatory polyarthritis that involves small peripheral joints, with articular and extra-articular manifestations.
- It is classified as an immune-mediated inflammatory disease (IMID).
Characteristics
- RA affects mostly women, with a female-to-male ratio of 3:1.
- It is characterized by synovial inflammation and hyperplasia, leading to joint damage and deformities.
Pathogenesis
- Adaptive and innate immunity play fundamental roles in initiating, propagating, and maintaining the autoimmune process of RA.
- T cells, B cells, antigen-presenting cells, and various cytokines are involved in the pathologic process.
- Abnormal production and regulation of proinflammatory and anti-inflammatory cytokines and cytokine pathways are found in RA.
Immune Cells
- T cells: produce pro-inflammatory cytokines, mediate T-cell activation, and stimulate macrophages and fibroblasts.
- B cells: secrete proteins supporting RA, such as rheumatoid factors (RFs) and anti-citrullinated protein antibodies (ACPAs).
- Macrophages: secrete cytokines, leading to inflammation and transforming into tissue-destructive cells.
- Synovial fibroblasts: proliferate, producing cytokines and chemokines, leading to bone erosion.
Laboratory Studies
- Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level: markers of inflammation.
- Complete blood count (CBC): hematologic parameters, including thrombocytosis, associated with disease activity.
- Rheumatoid factor (RF) assay, antinuclear antibody (ANA) assay, and anti-cyclic citrullinated peptide (anti-CCP) antibody: immunologic parameters.
Rheumatoid Factor (RF)
- An immunoglobulin (Ig) M antibody directed against the Fc fragment of IgG, present in approximately 60-80% of patients with RA.
- Predicts radiographic progression of bone erosions, independent of disease activity.
- Not specific for RA, also present in other connective tissue diseases, infections, and autoimmune disorders.
Anti-Citrullinated Protein Antibody (ACPA)
- Assays for anti-citrullinated protein antibody (ACPA; often tested as anti-CCP) are used clinically for diagnosing RA.
- ACPA-positive patients may have a more erosive RA disease course than ACPA-negative patients.
- The presence of both anti-CCP antibodies and RF is highly specific for RA, indicating a worse prognosis.
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Description
This quiz covers the definition and characteristics of Rheumatoid Arthritis, an autoimmune and chronic inflammatory disease that affects the joints.
