As far as I know, the adherence property of monocytes is not related with any functional state such as the "activation" but it is an intrinsec characteristic of monocytes

Hello Sharon

I work with monocytes. Monocytes have property to adherence by molecule adhesion on cell surface. This adherence is by integrins as CD49c, ITGAM, etc. The adherence show a cell activity because is a requirement to cell-differentiation into macrophage (primary culture). Monocytes, as adhesive cell, need have adherence for stimulating several cell function, besides avoiding anoikis processes. The anoikis is a apoptosis by losing adherence (cell-to-cell or cell-surface).

Best regards

Hello Sharon 

Monocytes require adherence (even to plastic surface) to get through differentiation to macrophages. Adherence is mediated by cell surface integrins. In some certain conditions, as for inflammation, the panel of surface integrins change over the time in some subpopulations of monocytes, such that some of them detach while some others remain attached and both have different phenotypic and functional characteristics.

Regards