Caracterização do padrão AC-28 em FAN HEp-2

Abstract

Autoantibodies may be associated with autoimmune diseases such as systemic lupus erythematosus and systemic sclerosis, although they can also be detected in individuals without clinical evidence of autoimmunity. The detection of these markers through indirect immunofluorescence (IIF) on HEp-2 cells is a valuable diagnostic tool in the investigation of such conditions. In Brazil, the standardization of antinuclear antibody (ANA) testing using HEp-2 cells is guided by brazilian consensus statements, while the International Consensus on ANA Patterns (ICAP) provides international guidelines. Recently, the mitotic pattern AC-28 (“mitotic chromosomal”) was incorporated into the 7th Brazilian Consensus on Autoantibodies (CBA), although its clinical relevance remains poorly understood. This study critically reviewed the literature on AC-28, addressing its immunological identity, the morphological features observed by IIF, and reports of possible clinical associations. Evidence suggests that this pattern, related to autoantibodies targeting modified histone H3 and the MCA-1 protein, may be associated with autoimmune diseases. However, its low frequency and limited positive predictive value warrant cautious interpretation. The inclusion of AC-28 in the CBA aims to align the national classification with international standards and to encourage further research to clarify its clinical significance.