Over-expression of anti-CD75 reactive proteins on distal and collecting renal tubular epithelial cells in calcium-oxalate stone-forming kidneys in Egypt.
OBJECTIVE
To assess the nature, distribution and expression pattern of CD75, a neuraminidase-sensitive lymphocyte cell surface differentiation antigen, in calcium oxalate (CaOx) stone disease, as cell-surface sialic acid might be involved CaOx crystal binding, and lectin-binding assays suggest that sialic acid in the alpha2,6 position is upregulated in stone-forming kidneys.


METHODS
Human CaOx stone-forming and normal kidneys (13 each) and primary kidney epithelial cells (CAKI-1, three samples) were analysed. The protein pattern, distribution and expression of CD75 were analysed using Western blotting, immunohistology and semi-quantitative confocal laser scanning microscopy (cLSM). Production was investigated by alpha2,6-sialyltransferase specific reverse transcription-polymerase chain reaction.


RESULTS
Western blotting showed one strong band at approximately 43 kDa that reacted with anti-CD75 when renal epithelial and CAKI-1 tumour cell extracts were analysed. However, in renal tissue extracts of CaOx stone formers there were additional bands at 120 and 205 kDa. Image processing after cLSM showed that anti-CD75 reactivity was significantly greater on E-cadherin-positive distal and collecting tubular cells from CaOx stone-forming kidneys, at a mean (sd) intensity of 87 (7), than on those from normal kidneys, at 41 (5) (P = 0.005).


CONCLUSIONS
CD75 expression in human kidney was primarily on the luminal surface of distal tubules and collecting ducts. Whether increased epithelial CD75 expression in CaOx stone disease is a cause or result of the disease remains to be clarified.
Kramer
G
G
Department of Urology, University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.
Steiner
G E
GE
Neumayer
C
C
Prinz-Kashani
M
M
Hohenfellner
M
M
Gomha
M
M
Ghoneim
M
M
Newman
M
M
Marberger
M
M
D015703:Antigens, CD / Q000378:metabolism*; D015153:Blotting, Western; D002129:Calcium Oxalate / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D007669:Kidney Calculi / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012799:Sialyltransferases; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
D015703:Antigens, CD; D002129:Calcium Oxalate; D012799:Sialyltransferases; C093493:ST6GAL1 protein, human; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase