Thymoma and paraneoplastic myasthenia gravis

Autoimmunity. 2010 Aug;43(5-6):413-27. doi: 10.3109/08916930903555935.

Abstract

Paraneoplastic autoimmune diseases associate occasionally with small cell lung cancers and gynecologic tumors. However, myasthenia gravis (MG) occurs in at least 30% of all patients with thymomas (usually present at MG diagnosis). These epithelial neoplasms almost always have numerous admixed maturing polyclonal T cells (thymocytes). This thymopoiesis-and export of mature CD4(+)T cells-particularly associates with MG, though there are rare/puzzling exceptions in apparently pure epithelial WHO type A thymomas. Other features potentially leading to inefficient self-tolerance induction include defective epithelial expression of the autoimmune regulator (AIRE) gene and/or of major histocompatibility complex class II molecules in thymomas, absence of myoid cells, failure to generate FOXP3(+) regulatory T cells, and genetic polymorphisms affecting T-cell signaling. However, the strong focus on MG/neuromuscular targets remains unexplained and suggests some biased autoantigen expression, T-cell selection, or autoimmunization within thymomas. There must be further clues in the intriguing serological and cellular parallels in some patients with late-onset MG but without thymomas-and in others with AIRE mutations-and in the contrasts with early-onset MG, as discussed here.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Autoantibodies / immunology
  • Autoantigens / immunology
  • Autoantigens / metabolism
  • Epithelial Cells / pathology
  • Genes, MHC Class II
  • Humans
  • Immunoglobulin G / immunology
  • Lymphopoiesis
  • Myasthenia Gravis / genetics
  • Myasthenia Gravis / immunology*
  • Myasthenia Gravis / physiopathology
  • Paraneoplastic Syndromes, Nervous System / genetics
  • Paraneoplastic Syndromes, Nervous System / immunology*
  • Polyendocrinopathies, Autoimmune / immunology
  • T-Lymphocytes / immunology
  • Thymoma / genetics
  • Thymoma / immunology*
  • Thymoma / pathology
  • Thymoma / physiopathology
  • Thymus Gland / physiopathology*
  • Transcription Factors / genetics

Substances

  • APECED protein
  • Autoantibodies
  • Autoantigens
  • Immunoglobulin G
  • Transcription Factors