Unfortunately, there is no fixed answer for that. It depends on how long the inflammatory stimuli last, the immune response capability of the host (healthy or other subclinical infection), age, dose of stimulus etc...In general, it also depends on the number of granulozytes and CD14+ monocytes being recruited, the number of CD16+ (M2) macrophages being present at the site of inflammation, the number of macrophages, DC, Langerhans cells being present before infection...so, you see, not easy to answer. In general, the time-frame is within a couple of hours of CD14+ monocytes maturing. Hope this helps?

Unfortunately, there is no fixed answer for that. It depends on how long the inflammatory stimuli last, the immune response capability of the host (healthy or other subclinical infection), age, dose of stimulus etc...In general, it also depends on the number of granulozytes and CD14+ monocytes being recruited, the number of CD16+ (M2) macrophages being present at the site of inflammation, the number of macrophages, DC, Langerhans cells being present before infection...so, you see, not easy to answer. In general, the time-frame is within a couple of hours of CD14+ monocytes maturing. Hope this helps?

From a sustained stimulus, most monocytes turn to be differentiated after 3 days at the time of delayed hypersensitivity granuloma. But the exact percentage is probably variable according to many parameters in a given experiment.

This is not really known. There are no good kinetic studies on monocyte differentiation in vivo. In vitro, it takes about 6 days for human blood monocytes to differentiate to macrophages.

In vivo all monocytes will differentiate if the stimulus is long and strong- also this can happen in a matter of hours. Transferred bone marrow monocytes can migrate into site and become effector cells within 12 hrs

The statement "it depends" is correct and perhaps most accurate. Of course there is more to this process then differentiation/maturation. Further, we need to differentiate between proliferation, commitment, differentiation, and activation. Indeed, in rodents and it appears clinically, extramedullary hematopoiesis (EMH) is also part of these processes. Under conditions of stress/danger signals hematopoietic progenitors circulate and arrest at sites of inflammation. These cells are rarely quantified; however, metamyelocytes and myelocytes in addition to segs are found at inflammatory sites. Indeed, in some instances they can be a majority of the myeloid cells observed. Timing of differentiation, as well as, linage commitment (granulocytic, dendritic, macrophage, endothelial and osteoclast) are all relevant and may have varying time courses. Studies of BrdU or Ki-67 staining and hematopoietic progenitors (CFU-GM) support the complexity of this seemingly simple question.

We found in an air-pouch mouse model with Leishmania infection that it takes approx. 16 hours for the first macrophages to infiltrate (in comparison: granulocytes require 2 - 4 hrs.) Unfortunately, we do not know their differentiation status before and after crossing the barrier (of the air-pouch) in detail. However, they are ready for phagocytosis, ROI and No formation.

An additional layer of complexity (at least in cancer associated inflammation) that different subtypes of myeloid-derived cells are recruited. These are characterized by predetermined differences in their capacity to differentiate. Thus, the statement 'it depends' is indeed one of the best descriptions.

I agree with Dr Becker. The rate of differentiation and the recruitment could depend on the kind of disease or animal model you are studying. Tumors, viral or bacterial infections could generate different microenvironments, resulting in different fates of differentiation. In our setting, tumor bearing mice and cancer patients, we observe a great recruitment of myeloid derived suppressor cells at tumor site. In this environment they predominantly differentiated in immune suppressive macrophages.