cell based colorimetric elisa protocol

[Claire84]

Hi guys,
I'm reading same protocols about whole-cell elisa and I find that cells for testing should be around 90% of confluent.
What does it mean?I don't have experience with cell culture and I'll appreciate all your suggestions!

Thank you in advance

[relaxin]

This meens that the cell density in the 96-well plate should be very high with a little empty space among the cells.

[CrowSan]

Hi - confluency is a way that cell growth can be measured (not very accurately) by eye. It is used for adherent cells.
When cells are 100% confluent they completely cover the surface they are growing on. When 50% confluent they cover half the surface area they are growing on. When 90% (as Relaxin pointed out) they are "almost" completely covering the surface area they are growing on. One persons "90%" may not be exactly another persons "90%" (I know this as we did a test within the group using a set of images with cells at different conluencies. I did quite badly in it!).
Hence I always give a bit of error rate when I state a conluence (either approximately: ~90% or ranged: 85-95%)
Hope this helps
CrSn