The thymus in seronegative myasthenia gravis patients

✍ Scribed by N. Willcox; Myriam Schluep; M. A. Ritter; J. Newsom-Davis

• Publisher: Springer
• Year: 1991
• Tongue: English
• Weight: 542 KB
• Volume: 238
• Category: Article
• ISSN: 0340-5354
• DOI: 10.1007/bf00319736

✦ Synopsis

In 5-10% of all patients with typical generalised myasthenia gravis (MG), serum antibody to the acetylcholine receptor (AChR) is undetectable. To determine whether these represent a distinct subgroup, we have compared the thymuses of 14 seronegatives, 70 seropositives and 12 non-myasthenic controls. By quantitative immunohistology on coded sections, the 7 seronegative samples were clearly distinguishable from the controls by the pronounced lymph node-type T-cell areas in the medulla. While these closely resembled those in the seropositive cases, germinal centres were significantly sparser, and total in vitro IgG production was disproportionately low (per B cell) in the 12 cases tested. Furthermore, specific anti-AChR production was never detected in any of these cultures. The data support the view that the medullary T-cell areas are the most consistent abnormality in the MG thymus (though it may not be primary), and they strongly imply that seronegative and seropositive MG are distinct entities.