Monocytes seem to attach to plastic in serum free media, but then subsequently seem to detach rather easily. Presumably this is because they do not have much of an ECM to adhere to. Have you tried adding serum. Once they have started producing their own ECM, and are well adhered, then remove the sera if you have to grow in serum free media.

May we assume that you F/H the buffy coat prior to adding to the flask?  This will get rid of the reds and most of any remaining grands.  Since you are getting a buffy coat have you considered using a mononuclear cell apheresis product?  This will give you a lot more monos and a higher concentration of monos to begin with.  i.e. 20-40%.  Alternatives include doing a Percol gradient separation but you end up with monos that have percol pinocytosized.  My approach is to use elutration of the PBMC that will provide about 85% pure monos.  This way you don't worry about sticking to plastic to enrich.  As suggested above you can use serum, human or FBS.  FBS works better, but is not autologous. 

Why do you want the monos to stick other than to enrich them.  If you are culturing to become DCs or macs who cares.  Get a population that is >85% pure and culture in teflon, non-adherent bags. 

Thank you for your answers!!, I do F/H the buffy coats, and I want the monocytes for derive to DCs. Can you recommend me any teflon bags? or a protocol to derive DCs in bags?

thanks again

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