Thymic extracellular matrix in myasthenia gravis. II. Immunohistochemical evidence for increased type I collagen degradation.
By immunohistochemistry, we studied the breakdown of type I collagen in frozen sections of normal and hyperplastic (myasthenia gravis-associated) human thymuses. This analysis was carried out using a specific polyclonal antibody directed against the alpha 2-CB(3,5) peptide, a degradation product of type I collagen. In the normal thymus, virtually no labeling was observed within thymic septae or intralobular regions. In contrast, bright fluorescent staining was consistently detected in myasthenia gravis-associated hyperplastic thymuses. Such immunoreactivity was found not only in septal regions but also in the intralobular connective tissue meshwork that exists in these thymuses. Our results represent further evidence for a defect in extracellular matrix metabolism in hyperplastic thymuses, which may be related to the abnormal intrathymic penetration of B cells, known to occur in this disease.
Savino
W
W
Department of Immunology, Institute Oswaldo Cruz, FIOCRUZ-Manguinhos, Rio de Janeiro, Brazil.
Emonard
H
H
Grimaud
J A
JA
D000293:Adolescent; D000328:Adult; D002675:Child, Preschool; D003094:Collagen / Q000145:classification / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D006801:Humans; D006965:Hyperplasia; D007150:Immunohistochemistry; D007223:Infant; D009157:Myasthenia Gravis / Q000378:metabolism* / Q000473:pathology; D012016:Reference Values; D013950:Thymus Gland / Q000378:metabolism* / Q000473:pathology
D003094:Collagen