Hi Echo Zhu

CD11b is not specific to microglia:

• While CD11b is a marker highly expressed on microglia, it's also present on other immune cells, particularly macrophages.
• This means that CD11b staining alone might include contaminating cells from the periphery, especially if the isolation process wasn't very stringent.
• CD11b can be combined with IBA-1 or TMEM119 to evaluate the purity.

Hope it helps,

Thanks,

CD11c is typically used to identify disease associate microglia (DAM).

See:

Article A Unique Microglia Type Associated with Restricting Developm...

Article Microglial subtypes: diversity within the microglial community

Perhaps the studies you refer to are looking for a subtype of microglia?

For purity, combinations of CD11b and CD45 are typically accepted, but markers such as P2Ry12 and Cx3cr1 are great for a final gate in the Flow Cytometry process. I typically would see 97-98% Cx3Cr1 positive microglia isolated from a Cd11bhigh / Cd45low gate as in Article Single-Cell RNA Sequencing of Microglia throughout the Mouse...

All of these markers have their caveats. For example, P2Ry12 expression is generally stable in microglia but will drop significantly during pathological situations. Cx3Cr1 is widely used for manipulating microglial gene expression in transgenic mouse models; however, it is also expressed on peripheral immune cells.

Good luck with your studies!