We strongly advise against overnight incubation.
The Monocyte Attachment Medium does not contain cytokines/survival factors for the monocytes. If the cells remain in the Monocyte Attachment Medium for longer than 2 hours, they will go into apoptosis and die. The lymphocytes will survive longer. Some of them will attach after such a long time and then cannot be washed off.
Therefore, overnight attachment is absolutely inappropriate. However, if time is short, monocyte attachment can be shortened to 1 hour. To do this, it is best to add Monocyte Attachment Medium to the culture vessels in advance and equilibrate it in the incubator. Remove the vessels from the incubator only briefly to add the appropriate amount of concentrated PBMC suspension. Then, even after 1 hour, most of the monocytes are attached.