Effect of red blood cells on shear-induced honotypic aggregation of human neutrophils

Goldsmith, H.; Mcintosh, F.; Spanos, C.

FASEB Journal 17(4-5): Abstract 100


ISSN/ISBN: 0892-6638
Accession: 034803828

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Steady application of a threshold shear rate in a cone and plate rheoscope has been shown to support homotypic aggregation of unstimulated human neutrophils. Previous work showed that the presence of red cells at 40% hematocrit significantly affects the 2-body collision frequency and collision doublet lifetimes, (exp, of platelet-size latex microspheres. Here we studied 2-body collisions of isolated neutrophils in transparent suspensions of 40% (v/v) red cell ghosts in plasma using high speed videomicroscopy. We determined the mean <(exp> and the two-body collision efficiency,(= % collisions leading to formation of non-separating doublets (those rotating past the orientation predicted for break-up of doublets of inert spheres). As previously found in the absence of ghost cells, at low shear rate, G = 14 s-1, very few non-separating doublets formed,(= 1%, but <(exp> was 28% greater than <(theor> predicted for inert spheres. At G = 110 s-1,(=5.3% and normalized mean lifetime, (n = <(exp>/<(theor> = 1.3, much less than in the absence of ghost cells (29.4% and 2.1, respectively). At G = 220 s-1,(= 39.8% and Tn = 3.7, greater than in the absence of ghost cells (20.6% and 2.1, respectively), but the % neutrophils in large aggregates after 10 s shear = 40%, compared to 72% in the absence of ghost cells. Thus, although the ghost cells suppress the formation of larger aggregates, they lengthen doublet lifetimes.