Abstract
l-selectin is constitutively expressed on most leukocytes and is responsible for the initial events in cell trafficking termed tethering and rolling. Recently, l-selectin has been shown to associate with the actin-based cytoskeleton under a variety of conditions. In an effort to better understand l-selectin cytoskeletal association and the ultrastructural nature of the cytoskeleton itself, we provide a comparison of the cytoskeletal association of various human and bovine surface proteins in relation to l-selectin. Electron microscopic examination of the cytoskeleton provided further data on the ultrastructure of freshly isolated peripheral lymphocytes as well as demonstrated l-selectin localization to the periphery of the cytoskeleton following low dose detergent treatment of the cell. Clusters of colloidal-gold-stained l-selectin were found on the surface of the detergent-treated lymphocytes, even though these particles completely lacked microvilli. By flow cytometry, we have defined three distinct patterns of cytoskeletal association; constitutive, inductive, and mAb crosslink-induced, and assigned human and bovine CD2, CD3, CD4, CD5, CD8, CD18, CD19, CD44, CD45RA, CD45RO, αβ TCR, γδ TCR, e-selectin ligands, and l-selectin surface antigens to one of these respective patterns. SDS–PAGE analyses confirmed most of the flow cytometry results. Depending upon its conformation, l-selectin fell into the inductive or mAb crosslink-induced pattern of association, similar to e-selectin ligand(s). Our data provide additional insight into the functional role of l-selectin and the cytoskeleton in immunological events.
Published Version
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