Work

Distribution and clinical significance of anti-TIF1-γ autoantibody isotypes and IgG subclasses in patients with dermatomyositis

Year: 2026

Type: article

Abstract: Objectives Anti-transcriptional intermediary factor 1-γ (TIF1-γ) antibody is strongly associated with cancer in patients with dermatomyositis (DM), yet the clinical relevance of its isotypes and IgG subclasses remains unclear. This study aimed to evaluate the prognostic value of anti-TIF1-γ isotypes and IgG subclasses for cancer risk and mortality in patients with DM.Methods Serum samples from 95 patients with anti-TIF1-γ-positive DM were analysed for anti-TIF1-γ isotypes (IgG, IgA, IgM) and IgG subclasses (IgG1–4) using ELISA. Clinical data were collected retrospectively. Multivariable Cox proportional regression was used to identify factors associated with mortality.Results Among the 95 patients with anti-TIF1-γ-positive DM, 54 (56.84%) were diagnosed with cancer and 14 died from cancer. Positivity rates were 100.0% for isotypes IgG of anti-TIF1-γ, 49.5% for IgA and 0.0% for IgM. For IgG subclasses, positivity rates were IgG1 93.7%, IgG2 53.7%, IgG3 97.9% and IgG4 51.6%. The most frequent antibody profiles were IgG1 +IgG2+IgG3+IgA+ (21.1%), IgG1+IgG3+IgG4+ (21.1%), IgG1+IgG2+IgG3+IgG4+ (15.8%) and IgG1+IgG3+IgA+ (13.7%). Cancer incidence was 100% (36/36) in patients with an IgA+/IgG4⁻ profile vs 10.53% (4/38) in those with an IgA⁻/IgG4+ profile. IgG4 was negatively associated with cancer, whereas IgA showed a strong positive association (both p<0.001). Multivariable analysis confirmed that the absence of anti-TIF1-γ IgG4 and the presence of anti-TIF1-γ IgA were associated with increased mortality.Conclusions The combination of anti-TIF1-γ IgA positivity and IgG4 negativity may serve as biomarkers for stratifying cancer risk and predicting mortality in patients with anti-TIF1-γ-positive DM.

Source: RMD Open

DOI: 10.1136/rmdopen-2026-007293