The effect of LPS, uraemia, and haemodialysis membrane exposure on CD14 expression in mononuclear cells and its relation to apoptosis.
BACKGROUND
Both uraemia and bioincompatible haemodialysis membranes induce mononuclear cell apoptosis. Recent reports demonstrate that spontaneous apoptosis in normal monocytes is associated with the down-regulation of CD14 molecules, whereas LPS which prevents the down-regulation of CD14 favours monocyte survival. The aim of the present study was to evaluate a possible association between mononuclear cell apoptosis and low expression of CD14 molecules. This study also investigated whether LPS affects mononuclear cell CD14 expression and the apoptosis induced by uraemia and exposure to Cuprophan (CU) membrane.


METHODS
The study was performed in vitro examining the effects of CU membrane and LPS on mononuclear cells from normal subjects and from end-stage renal failure patients. Cells were analysed by flow cytometry with fluorescent monoclonal antibodies to determine CD14 expression and with Annexin-V labelling to determine apoptosis.


RESULTS
In mononuclear cells from uraemic patients cultured for 48 h, there was a subset of cells with low CD14 expression; this subset of cells was not observed in normal monocytes cultured for the same period of time. Cells with low CD14 expression were also observed when normal or uraemic mononuclear cells were cultured in the presence of CU membrane. Simultaneous measurement of apoptosis and CD14 expression revealed that cells with low CD14 expression underwent apoptosis. The addition of LPS to the medium markedly reduced the number of mononuclear cells with low CD14 expression and also reduced the rate of apoptosis in these cells.


CONCLUSIONS
Our data suggest that mononuclear cell apoptosis induced by uraemia and the CU membrane is associated with low CD14 expression. Furthermore, LPS prevented the decrease in CD14 and reduced the rate of apoptosis.
Carracedo
Julia
J
Unidad de Investigación, Servicio de Nefrología, Hospital Universitario Reina Sofía, Córdoba, Spain.
Ramírez
Rafael
R
Martin-Malo
Alejandro
A
Rodríguez
Mariano
M
Aljama
Pedro
P
D000328:Adult; D000368:Aged; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D016022:Case-Control Studies; D002482:Cellulose / Q000009:adverse effects / Q000031:analogs & derivatives*; D015536:Down-Regulation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007688:Kidneys, Artificial / Q000009:adverse effects*; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects* / Q000276:immunology*; D018950:Lipopolysaccharide Receptors / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000633:toxicity*; D008567:Membranes, Artificial; D008875:Middle Aged; D014511:Uremia / Q000097:blood / Q000276:immunology*
D017304:Annexin A5; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008567:Membranes, Artificial; D002482:Cellulose; C009865:cuprammonium cellulose