Analysis of selective mobilization of L-selectin and Mac-1 reservoirs in bovine neutrophils and eosinophils.
Following activation of granulocytes, L-selectin (CD62L) is generally shed from the cellular surface, whereas Mac-1 (CD11b/CD18) expression is well known to increase. However, a number of studies in bovines and humans show that the expression of L-selectin may increase as well. This urged us to examine the possible existence of both L-selectin and Mac-1 reservoirs in bovine neutrophil and eosinophil populations through the use of flow cytometry in combination with an optimized method for cell membrane permeabilization. Augmented L-selectin and Mac-1 expression was detected in both granulocyte populations upon saponin treatment. Confocal microscopic studies indicated that both molecules exhibit a different pattern of subcellular localization. Incubation with sialidase revealed the existence of hidden L-selectin epitopes at the cell surface, while no additional Mac-1 epitopes were exposed. Platelet-activating factor stimulation decreased surface and total expression of L-selectin to the same extent in both populations, but solely affected Mac-1 surface expression on eosinophils. Moreover, cytoskeletal actin filaments and microtubules were found to be involved in the regulation of Mac-1 surface expression on bovine neutrophils and eosinophils. In marked contrast, expression of L-selectin was minimally affected by cytoskeleton perturbing agents. The present study indicates that L-selectin and Mac-1 adhesion molecules reside in distinctly located reservoirs in bovine granulocytes and can be selectively mobilized upon in vitro stimulation.
Diez-Fraile
Araceli
A
Department of Physiology, Biochemistry and Biometrics, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
Meyer
Evelyne
E
Paape
Max J
MJ
Burvenich
Christian
C
D000818:Animals; D002417:Cattle; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004804:Eosinophils / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects; D019041:L-Selectin / Q000378:metabolism*; D016177:Macrophage-1 Antigen / Q000378:metabolism*; D009439:Neuraminidase / Q000378:metabolism; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000494:pharmacology; D012503:Saponins / Q000494:pharmacology
D016177:Macrophage-1 Antigen; D010972:Platelet Activating Factor; D012503:Saponins; D019041:L-Selectin; D009439:Neuraminidase