I am planning to perform a phagocytosis assay for THP1-derived M2 macrophages. According to the Vybrant phagocytosis assay kit, it says to incubate the cells in the assay plate for an hour before adding the fluorescence particles. However, I am a little unsure whether an hour will be enough for the cells to adhere completely to the plate so that they don't get washed away in the following steps. I am also confused about whether a longer incubation time will impact the phagocytosis ability of the cells if they strongly adhere to the surface. Can anyone advise on the optimal time?