Optimization of antinuclear antibody-HEp-2 test

• Grant number: 18/25431-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2019
• End date: March 31, 2020
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Luiz Eduardo Coelho Andrade
• Grantee: João Victor Borges Gomes
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

Research into Antinuclear Antibody-HEp-2 Test (ANA / HEp-2) is an important pillar for the diagnosis of various autoimmune rheumatic diseases (ARDs). The title and fluorescence pattern obtained with a given sample is important for a correct interpretation of the test. The ANA / HEp-2 test has high sensitivity, being able to identify autoantibodies not only in patients with ARDs, but also in patients with inflammatory diseases and even in healthy individuals. This fact impairs the specificity of the ANA / HEp-2 test and may lead to problems in its interpretation in daily medical practice. The main hypothesis that may explain such positivity is related to the so-called natural autoantibodies, molecules existing in lower concentrations, with less acidity than the autoantibodies present in pathological conditions and that have their altered concentrations in inflammatory conditions. Therefore, estimating the avidity of the autoantibodies in positive samples in the ANA / HEp-2 test becomes interesting as a way of attempting to discriminate samples in which natural autoantibodies are present from those with autoantibodies that appear in pathological conditions, that is, those that have greater greed. We will select serum samples with different patterns and titles, from healthy individuals, patients with non-autoimmune diseases (multiple comorbidities, cancer, infectious diseases, and psychiatric diseases) and patients with ARDs. In the first phase of the study, these samples will be submitted to the conventional ANA / HEp-2 test and in parallel, a similar procedure will be executed, with the use of chaotropic solutions, which favor the elution of antibodies of low avidity. In the second stage of the project, new samples will be collected from 200 patients with ARDs, 200 from healthy individuals and 200 from patients with non-autoimmune diseases will be obtained. All of the samples will be submitted to the elution protocol deemed most appropriate during the first phase of the project. With all of the findings, we intend to evaluate if the elution maneuver provides better diagnostic performance during the analysis of the samples.