The thymus in seronegative myasthenia gravis patients.
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.
Department of Neurological Science, Royal Free Hospital School of Medicine, London, UK.
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N
Willcox
M
M
Schluep
M A
MA
Ritter
J
J
Newsom-Davis
D000293:Adolescent; D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D001323:Autoantibodies / Q000032:analysis; D002648:Child; D005260:Female; D006801:Humans; D006965:Hyperplasia; D007074:Immunoglobulin G / Q000032:analysis; D007150:Immunohistochemistry; D008297:Male; D009157:Myasthenia Gravis / Q000175:diagnosis / Q000276:immunology*; D011950:Receptors, Cholinergic / Q000276:immunology; D012698:Serologic Tests; D013950:Thymus Gland / Q000737:chemistry / Q000276:immunology* / Q000473:pathology
D015703:Antigens, CD; D001323:Autoantibodies; D007074:Immunoglobulin G; D011950:Receptors, Cholinergic