Effects of pro-inflammatory cytokines on apolipoprotein E secretion by a human astrocytoma cell line (CCF-STTG1)
✍ Scribed by Marjorie Starck; Philippe Bertrand; Stéphanie Pépin; Françoise Schiele; Gérard Siest; Marie-Madeleine Galteau
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 117 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0263-6484
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✦ Synopsis
Apolipoprotein (apo) E has been implicated in Alzheimer's disease; however, little is known about the regulation of its secretion in astrocytes. To investigate the eects of pro-in¯ammatory cytokines such as interleukin-1b (IL-1b), tumour necrosis factor-a (TNF-a) and interferon-g (IFN-g) on apoE secretion by CCF-STTG1 cells, a sensitive and speci®c double sandwich Enzyme-Linked ImmunoSorbent Assay (ELISA) was developed. Using a monoclonal antihuman apoE antibody as the capture antibody, this assay was carried out with commercially available reagents. The assay had a sensitivity of 0 . 013 ng per well, within-run and between-run variation coecients of 6 . 0 and 8 . 6 per cent respectively. There was no cross-reactions between antibodies used and apoAI, apoAII, apoB, apoCI, apoCII and apoCIII. Low apoE concentrations were assessed using a serum-free HepG2 culture medium as secondary calibrator, containing 59 mg l À1 of apoE. In serum-free medium, CCF-STTG1 cells secreted apoE, the accumulation of which in the cell medium increased linearly with time (27 mg per 48 h). After 48 h of incubation, apoE secretion was inhibited by TNF-a but not aected by IL-1b and IFN-g. However, the eect of regulatory factors may depend upon culture conditions since in the presence of 10 per cent fetal calf serum, IFN-g signi®cantly inhibited apoE secretion. Thus, apoE secretion by CCF-STTG1 cells is inhibited by speci®c pro-in¯ammatory cytokines. This new apoE ELISA presents the great advantage of using commercially available reagents which permit inter-laboratory comparability of results, involves relatively low cost and is adaptable for the measurement of low levels of apoE.