Analysis of selective mobilization of L-selectin and Mac-1 reservoirs in bovine neutrophils and eosinophils

Abstract

-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.bovine granulocyte / adhesion molecule reservoir / platelet-activating factor / cytoskeleton / sialidase

Migratory monocytes and granulocytes are major lymphatic carriers of Salmonella from tissue to draining lymph node

“…The upregulation of CD11b, also found for lymph granulocytes, can be related to their activation, allowing diapedesis through a vascular wall. However, CD62L was not reduced on lymph monocytes and granulocytes, although myeloid cell activation often leads (but not always) to shedding of this molecule [29].…”

Possible involvement of heparin-binding protein in transfusion-related acute lung injury

“…Increased surface expression of Mac-1 on neutrophils after stimulation with several stimulators, such as b-acetyl-g-O-alkyl-a-phosphatidylcholine, phorbol 12-myristate 13-acetate, or fMLP, has been well documented. 31,32 The expression of Mac-1 was significantly up regulated after incubation with heat-aggregated human IgG in comparison with non-heat-aggregated human IgG (Fig. 1A).…”

Possible involvement of heparin‐binding protein in transfusion‐related acute lung injury

“…An activation marker, Mac‐1 expression on the surface of neutrophils was then analyzed by FCM. Increased surface expression of Mac‐1 on neutrophils after stimulation with several stimulators, such as β‐acetyl‐γ‐ O ‐alkyl‐α‐phosphatidylcholine, phorbol 12‐myristate 13‐acetate, or fMLP, has been well documented 31,32 . The expression of Mac‐1 was significantly up regulated after incubation with heat‐aggregated human IgG in comparison with non–heat‐aggregated human IgG (Fig.…”