Myasthenia gravis: overlap with 'polyendocrine' autoimmunity.

Area of Science:

• Immunology
• Genetics
• Neurology

Background:

• Myasthenia gravis (MG) is an autoimmune disorder affecting neuromuscular junctions.
• The role of human leukocyte antigen (HLA) types and other autoimmune (AI) diseases in MG pathogenesis requires further elucidation.

Purpose of the Study:

• To investigate the association between specific HLA antigens (HLA-B8, HLA-DR3) and autoimmune disease prevalence in patients with myasthenia gravis.
• To determine the correlation between HLA types, acetylcholine receptor (AChR) antibody titers, and clinical presentation of MG.
• To explore the influence of age and sex on the expression of AI diseases and autoantibodies in MG patients.

Main Methods:

• Serological testing for organ-specific autoantibodies in 81 patients with spontaneously acquired myasthenia gravis.
• HLA-phenotyping for 77 patients.
• Analysis of antibody titers to acetylcholine receptors (AChR) and correlation with HLA antigens and clinical subgroups (ocular, generalized early/late onset, thymoma).

Main Results:

• Higher AChR antibody titers were observed in non-thymomatous MG patients with HLA-B8 and/or -DR3.
• Prevalence of overt AI diseases or subclinical AI disease varied across MG subgroups, with higher rates in generalized MG of late onset.
• HLA-B8 and -DR3 were associated with AI disorders in younger patients, particularly women, suggesting age-related breakdown of self-tolerance.

Conclusions:

• Specific HLA types (HLA-B8, -DR3), in conjunction with female sex, are significant factors for the early expression of myasthenia gravis.
• Ageing appears to facilitate the breakdown of self-tolerance, contributing to the development of autoimmune conditions.
• Ocular MG patients exhibit restricted autoimmune reactivity compared to other MG subgroups.