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Antineutrophil cytoplasm antibody: positivity and clinical correlation
Goitybell Martínez Téllez1, Bárbara Torres Rives1, Suchiquil Rangel Velázquez1
1Laboratorio de Inmunología, Centro Nacional de Genética Médica, La Habana, Cuba.
Insights
Anti-neutrophil cytoplasmic antibodies (ANCA) testing is valuable for diagnosing vasculitis, especially when confirmed with ELISA. Antinuclear antibodies (ANA) can interfere, but specific assays improve diagnostic accuracy.
Area of Science:
- Immunology
- Rheumatology
- Clinical Diagnostics
Background:
- Anti-neutrophil cytoplasmic antibodies (ANCA) are crucial biomarkers in autoimmune diseases.
- Antinuclear antibodies (ANA) can interfere with ANCA testing, potentially affecting diagnostic accuracy.
- Accurate ANCA determination is vital for diagnosing conditions like vasculitis.
Purpose of the Study:
- To evaluate the positivity and clinical relevance of ANCA testing.
- To assess the impact of antinuclear antibodies (ANA) interference on ANCA results.
- To determine the optimal methods for ANCA detection and confirmation.
Main Methods:
- Prospective study involving 267 patients indicated for ANCA testing.
- ANCA and ANA determined by indirect immunofluorescence with varying cut-off points.
- Anti-proteinase 3 and anti-myeloperoxidase antibodies measured by ELISA.
Main Results:
- ANCA positivity was highest in ANCA-associated vasculitides, rheumatoid arthritis, and systemic lupus erythematosus.
- ANCA presence without specific antigen positivity was more frequent in patients with ANA.
- Indirect immunofluorescence with a 1/80 cut-off, confirmed by ELISA, yielded the highest sensitivity and specificity for vasculitis diagnosis.
Conclusions:
- ANCA can be detected in various chronic inflammatory and autoimmune disorders.
- Combined indirect immunofluorescence and ELISA offer significant diagnostic value for vasculitis.
- Anti-myeloperoxidase assay is more useful than formalin assay in the presence of ANA.
Objective:
To determine positivity and clinical correlation of anti-neutrophil cytoplasmic antibodies (ANCA), taking into account the interference of antinuclear antibodies (ANA).
Material And Methods:
A prospective study was conducted in the Laboratory of Immunology of the National Cuban Center of Medical Genetic during one year. Two hounded sixty-seven patients with indication for ANCA determination were included. ANCA and ANA determinations with different cut off points and assays were determined by indirect immunofluorescense. Anti proteinase 3 and antimyeloperoxidase antibodies were determined by ELISA.
Results:
Most positivity for ANCA was seen in patients with ANCA associated, primary small-vessel vasculitides, rheumatoid arthritis and systemic lupus erythematosus. Presence of ANCA without positivity for proteinase 3 and myeloperoxidase was higher in patients with ANA and little relation was observed between the perinuclear pattern confirmed in formalin and specificity by myeloperoxidase. Highest sensibility and specificity values for vasculitides diagnostic were achieved by ANCA determination using indirect immunofluorescense with a cut off 1/80 and confirming antigenic specificities with ELISA.
Conclusion:
ANCA can be present in a great number of chronic inflammatory or autoimmune disorders in the population studied. This determination using indirect immunofluorescence and following by ELISA had a great value for vasculitis diagnosis. Anti mieloperoxidasa assay has a higher utility than the formalin assay when ANA is present.
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