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.
Willcox
N
N
Department of Neurological Science, Royal Free Hospital School of Medicine, London, UK.
Schluep
M
M
Ritter
M A
MA
Newsom-Davis
J
J
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