Expression of OX40 and OX40 ligand (gp34) in the normal and myasthenic thymus.
OBJECTIVE
To examine the expression of OX40, an activated memory T-cell marker, and its ligand (OX40L), a set of molecules for T-cell-B-cell interaction, and other lymphocyte activation markers in the thymuses of myasthenia gravis (MG) and controls.


METHODS
We studied the expression of OX40, OX40L, IL-2Ralpha and HLA-DR in the thymic tissues of MG and controls using immunocytochemistry and flowcytometry.


RESULTS
In both hyperplastic thymus of MG and control thymus, OX40+ cells were scattered mainly in the medulla with much fewer OX40L+ cells being distributed in the corticomedullary junctions. IL-2Ralpha and HLA-DR were expressed in the medulla at higher frequencies as compared with OX40 in controls as well as MG. In contrast, the numbers of OX40+ cells around the germinal centers (GC) were significantly greater than those of control thymuses, and some mononuclear cells in GC were OX40L+. A considerable number of OX40+ cells were seen in the thymic tissues adjacent to thymomas. OX40+ cells were CD4+ CD8- or CD4+ CD8+ and were mostly HLA-DR-. (The coexpression of OX40 and IL-2Ralpha on activated CD4+ T cells was previously reported.)


CONCLUSIONS
OX40, expressed in a fraction of activated CD4+ T cells, may be upregulated in thymic tissues adjacent to GC and thymoma in MG, and OX40 may interact with OX40L in GC to enhance anti-acetylcholine receptor antibody production in MG.
Onodera
J
J
Department of Neurology, Tohoku University School of Medicine, Sendai, Japan.
Nagata
T
T
Fujihara
K
K
Ohuchi
M
M
Ishii
N
N
Sugamura
K
K
Itoyama
Y
Y
D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006684:HLA-DR Antigens / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008297:Male; D008526:Medulla Oblongata / Q000378:metabolism; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000235:genetics* / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics* / Q000378:metabolism*; D013950:Thymus Gland / Q000378:metabolism* / Q000473:pathology
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D006684:HLA-DR Antigens; D008024:Ligands; D018124:Receptors, Tumor Necrosis Factor