Nephrology Dialysis Transplantation, Vol 12, Issue 3 465-469, Copyright © 1997 by Oxford University Press
AH Yang and JY Chen
BACKGROUND: alpha 2-macroglobulin (alpha 2M) is a glycoprotein involved in
delivery of growth factors, regulation of matrix degrading enzymes and
modulation of fibrinolysis factors, all of which are considered as
important pathogenic mechanisms of glomerular injury. However, the role of
alpha 2M in glomerular disease has not been extensively studied. The
amount, frequency and local distribution of alpha 2M in diseased glomeruli
are similarly undetermined. METHODS: Two hundred and fifty renal biopsy
cases with glomerular disease were collected. The glomerular deposition of
alpha 2M was surveyed with immunofluorescence- microscopy and
intraglomerular localization of alpha 2M was assessed by
immunoelectron-microscopy. To clarify the relationship between circulatory
concentration and local deposition of alpha 2M, serum samples were
collected at time of biopsy and alpha 2M was determined using radial
immunodiffusion assay. RESULTS: The amount and frequency of local
deposition of alpha 2M in glomeruli varied from disease to disease, and the
average positive rate was approximately 20%. Patients with minimal-change
nephrotic syndrome and IgM nephropathy not only had the highest mean serum
alpha 2M concentration but also exhibited higher frequency of glomerular
deposition of alpha 2M (25.9 and 30% respectively). The local deposition of
alpha 2M revealed by optical and electron-microscopy may not be directly
related to the high serum level of alpha 2M. The deposited alpha 2M was
observed to associate with electron-dense deposits, mesangial matrix and
mesangial cells. CONCLUSIONS: To our knowledge, this is the first report
that reveals the ultrastructural distribution of alpha 2M in glomerular
disease. The relatively selective deposition of alpha 2M in some glomerular
diseases strongly indicates that alpha 2M may play an active role in the
modulation of local inflammatory reaction and tissue repair in these
glomerular diseases.
ORIGINAL ARTICLES
Glomerular deposition of alpha 2-macroglobulin in glomerular diseases
Department of Pathology and Laboratory Medicine, Veterans General Hospital, Taipei, Taiwan.
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