I have been doing flow cytometry to investigate the innate immune cells present at the site of infection (in mice) with different Leishmania mutants at different time-points. I would like to know what percentage of inflammatory monocytes differentiate into macrophages and dendritic cells at the site of infection and the time-frame in which this occurs.
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.
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.
- Badges
- Science topic
- Similar topics
- Biological Science
- Immunology