Novel Antibodies Reactive with Sialyl Lewis X in Both Humans and Mice Define Its Critical Role in Leukocyte Trafficking and Contact Hypersensitivity Responses

Sialyl Lewis X (sLe(x)) antigen functions as a common carbohydrate determinant recognized by all three members of the selectin family. However, its expression and function in mice remain undefined due to the poor reactivity of conventional anti-sLe(x) monoclonal antibodies (mAbs) with mouse tissues. Here, we developed novel anti-sLe(x) mAbs, termed F1 and F2, which react well with both human and mouse sLe(x), by immunizing fucosyltransferase (FucT)-IV and FucT-VII doubly deficient mice with 6-sulfo-sLe(x)-expressing cells transiently transfected with an expression vector encoding CMP-N-acetylneuraminic acid hydroxylase. F1 and F2 specifically bound both the N-acetyl and the N-glycolyl forms of sLe(x) as well as 6-sulfo-sLe(x), a major ligand for L-selectin expressed in high endothelial venules, and efficiently blocked physiological lymphocyte homing to lymph nodes in mice. Importantly, both of the mAbs inhibited contact hypersensitivity responses not only when administered in the L-selectin-dependent sensitization phase but also when administered in the elicitation phase in mice. When administered in the latter phase, F1 and F2 efficiently blocked rolling of mouse leukocytes along blood vessels expressing P-and E-selectin in the auricular skin in vivo. Consistent with these findings, the mAbs blocked P-and E-selectin-dependent leukocyte rolling in a flow chamber assay. Taken together, these results indicate that novel anti-sLe(x) mAbs reactive with both human and mouse tissues, with the blocking ability against leukocyte trafficking mediated by all three selectins, have been established. These mAbs should be useful in determining the role of sLe(x) antigen under physiological and pathological conditions.

唾液酸化路易斯X（sLe(x)）抗原作为一种被选择素家族所有三个成员识别的常见碳水化合物决定簇发挥作用。然而，由于常规抗sLe(x)单克隆抗体（mAbs）与小鼠组织的反应性较差，其在小鼠中的表达和功能仍未明确。在此，我们通过用编码CMP - N - 乙酰神经氨酸羟化酶的表达载体瞬时转染表达6 - 硫酸化 - sLe(x)的细胞来免疫岩藻糖基转移酶（FucT） - IV和FucT - VII双缺陷小鼠，开发了新型抗sLe(x) mAbs，称为F1和F2，它们与人和小鼠的sLe(x)都有良好反应。F1和F2特异性结合sLe(x)的N - 乙酰基和N - 羟乙酰基形式以及6 - 硫酸化 - sLe(x)（一种在高内皮微静脉中表达的L - 选择素的主要配体），并有效地阻断小鼠淋巴细胞向淋巴结的生理性归巢。重要的是，这两种mAbs不仅在L - 选择素依赖的致敏阶段给药时，而且在小鼠的激发阶段给药时都能抑制接触性超敏反应。在后一阶段给药时，F1和F2有效地阻断小鼠白细胞在体内耳郭皮肤中沿表达P - 和E - 选择素的血管的滚动。与这些发现一致，mAbs在流动小室试验中阻断了P - 和E - 选择素依赖的白细胞滚动。综上所述，这些结果表明，已经建立了对人和小鼠组织都有反应且具有阻断所有三种选择素介导的白细胞运输能力的新型抗sLe(x) mAbs。这些mAbs在确定生理和病理条件下sLe(x)抗原的作用方面应该是有用的。