White blood cells (WBCs) are part of our immune system, performing various organism defense functions. In order to reach the sites of action, they have to migrate to the vessel walls through a process called margination. The hematocrit (Ht), also known as packed cell volume (PCV), is the volume fraction of red blood cells (RBCs) in blood. Ht is typically of the order of 0.4 to 0.5 in arterioles and can achieve 0.16 to 0.20 in small vessels. My question is, how do these changes in hematocrit affect the margination of WBCs and thus their efficiency in the immune system?
My colleagues has done theoretical/simulation studies concerning that problem:
'Margination of White Blood Cells in Microcapillary Flow'
http://dx.doi.org/10.1103/PhysRevLett.108.028104
, it might be interesting for you.
The higher the hematocrit the more less deformable cells, such as leucocytes, will experience margination. Lim et al showed this in a microfluidics system - http://pubs.rsc.org/en/content/articlelanding/2010/lc/c003873c#!divCitation
Thanks Jason for your answer. However, do you think that when the Ht is high enough, the RBCs will be expelled to the blood vessel center and thus a high WBC margination toward the walls is expected. Do you think that there is a competition effect between this phenomena which is caused by the high concentration of the RBCs and the WBC deformability that you mentioned? Thanks!
My colleagues has done theoretical/simulation studies concerning that problem:
'Margination of White Blood Cells in Microcapillary Flow'
http://dx.doi.org/10.1103/PhysRevLett.108.028104
, it might be interesting for you.
Yes, it is slightly more complicated than my first answer... How margination depends on hematocrit, WBC deformability (and RBC aggregation) is nicely shown in simulations by Fedosov (Margination of white blood cells in micro capillary flow, PRL 108, 028104(2012)). I am not an expert but i hope this helps.
Absolutely! I have only just starting contributing and i was more worried about etiquette :) Say hello to Dmitry, we also collaborate on a project.
I think that Fedosov et al. in their work observed that the strongest margination effect was in the range of Ht = 0.25 - 0.35, thus margination is attenuated at both lower and higher Ht values and that is indeed contradictory to their expectation. They do not tell anything about the why does margination decrease for high Ht??
@Jason: I will do so...
@Abdallah: Sorry, I am not in the WBC business, but why don't contact Dmitry Fedosov directly: https://www.researchgate.net/profile/Dmitry_Fedosov/
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