How would you distinguish peripheral monocytes from tissue macrophages with IHC? Specifically, I am interested in looking at rodent brain tissue. Any help is appreciated!
Could you tell us a few more specifics about what you are trying to achieve? specifically monocyte and macrophage ratios? what about monocyte subsets? M1/M2 macrophage ratios?
To start:
Ly-6C (ER-MP20), distinct mouse blood monocyte subsets can be distinguished: immature Ly-6Chi monocytes are recruited to acute peripheral inflammation and develop into Ly-6C+ exudate macrophages, whereas more mature Ly-6C-/lo monocytes are precursors for tissue macrophages and dendritic cells in steady state.
I have naive and injured rat brain tissue fixed in 4% PFA, frozen in OCT, and cut at 20um. I expect some monocyte infiltration in the injured tissue. I would like to stain the tissue with markers for peripheral monocytes and microglia to quantify cell number. I have seen a lot of papers distinguishing between monocytes and microglia with flow cytometry, but haven't found a good paper using IHC. I have stained for Iba1, but there are a lot of other markers out there like CD68, F4/80, and CSF1R, to name a few. We expect to see resting and activated microglia in the injured tissue. I have never stained for peripheral monocytes, and not super familiar with different subsets of monocytes... Still learning. I was given the task of "stain for peripheral monocytes and microglia (tissue macrophages) in the brain" as a quick and dirty side project. Thanks again for any help!
I am leaning towards using CCR2, CD34, & CD117 as markers for peripheral cells... I think I'll stay with Iba1 for microglia... But considering F4/80 and CD68 in the future...