Steeber D A, Engel P, Miller A S, Sheetz M P, Tedder T F
Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA.
J Immunol. 1997 Jul 15;159(2):952-63.
L-selectin is a cell surface adhesion receptor that mediates leukocyte rolling along vascular endothelium at sites of inflammation and lymphocyte attachment to endothelial cells within peripheral lymphoid tissues. Since ligation of L-selectin through its ligand recognition region may mimic physiologic ligand binding, a new panel of mAbs that engaged a conserved ligand-binding region within the lectin domains of human, mouse, and rat L-selectin were generated using L-selectin-deficient mice. Indeed, appropriate ligation of L-selectin generated transmembrane signals that resulted in immediate intercellular adhesion following cell-cell contact of lymphocytes, neutrophils, and L-selectin cDNA-transfected cells. Ab binding to only some epitopes within the lectin domain of L-selectin induced adhesion, while mAb binding to numerous other epitopes or other domains of L-selectin had no effect. PPME (yeast polyphosphomonoester core polysaccharide), a complex carbohydrate that mimics the natural L-selectin ligand, also induced potent intercellular adhesion. The induction of intercellular adhesion required cellular energy, an intact cytoskeleton, and cytoplasmic kinase activity as well as the membrane proximal and cytoplasmic domains of L-selectin. Therefore, ligation of L-selectin through specific ligand-binding epitopes identified by the mAbs generated in this study can generate transmembrane signals. Signaling through L-selectin may enhance leukocyte-endothelial cell interactions by serving as an activation/priming step during rolling, thereby promoting subsequent firm cell-cell adhesion in the presence of inflammatory mediators.
L-选择素是一种细胞表面黏附受体，它介导白细胞在炎症部位沿血管内皮滚动，以及淋巴细胞与外周淋巴组织内的内皮细胞附着。由于通过其配体识别区域连接L-选择素可能模拟生理性配体结合，因此利用L-选择素缺陷小鼠制备了一组新的单克隆抗体，这些抗体作用于人、小鼠和大鼠L-选择素凝集素结构域内的保守配体结合区域。事实上，L-选择素的适当连接产生跨膜信号，导致淋巴细胞、中性粒细胞和L-选择素cDNA转染细胞在细胞间接触后立即发生细胞间黏附。抗体仅与L-选择素凝集素结构域内的某些表位结合可诱导黏附，而与L-选择素的许多其他表位或其他结构域结合的单克隆抗体则无作用。PPME（酵母多磷酸单酯核心多糖）是一种模拟天然L-选择素配体的复合碳水化合物，也可诱导强烈的细胞间黏附。细胞间黏附的诱导需要细胞能量、完整的细胞骨架、细胞质激酶活性以及L-选择素的膜近端和细胞质结构域。因此，通过本研究中产生的单克隆抗体鉴定的特定配体结合表位连接L-选择素可产生跨膜信号。通过L-选择素发出的信号可能通过在滚动过程中作为激活/启动步骤来增强白细胞与内皮细胞的相互作用，从而在存在炎症介质的情况下促进随后牢固的细胞间黏附。
