Carlow D A, Ardman B, Ziltener H J
The Biomedical Research Centre, University of British Columbia, Vancouver, Canada.
J Immunol. 1999 Aug 1;163(3):1441-8.
The mAb 1B11 has been characterized as recognizing the activation-associated glycoform of murine CD43, a heavily O-glycosylated protein implicated in leukocyte homing. When hemopoietic cells from CD43-/- mice were stained with 1B11, CD43-independent binding of 1B11 was observed on peripheral CD8 T cells and at low levels on thymocytes, while no binding was detected on CD4 T cells, B cells, or bone marrow cells. Levels of 1B11 staining were comparable in lymph node CD8+ T cells from both CD43-/- mice and CD43+/+ mice. We sought to identify the CD43-independent target of 1B11 expressed on CD8 T cells. Previous work had demonstrated that neuraminidase treatment of lymph node cells (LNC) enhanced 1B11 binding on CD43+/+ LNC; this enhancement was also observed in CD43-/- LNC. We show that neuraminidase-enhanced 1B11 binding in CD43-/- LNC and EL4 thymoma cells is CD43 independent and that 1B11 detects a novel target of apparent mass of approximately 200 kDa identified as a hyposialylated form of CD45RB preferentially expressed on peripheral CD8, but not CD4, T cells. Our data also show that the recognition of CD43 and CD45RB by 1B11 is differentially affected by O-linked glycosylation and sialic acid. Whereas 1B11 recognition of CD43 on activated T cells required both core 2 O-glycan branching and sialic acid, 1B11 recognition of CD45 only occurred in the absence of both core 2 glycosylation and sialic acid.
单克隆抗体1B11已被鉴定为可识别小鼠CD43的激活相关糖型，CD43是一种高度O-糖基化的蛋白质，与白细胞归巢有关。当用1B11对CD43基因敲除小鼠的造血细胞进行染色时，在周围CD8 T细胞上观察到1B11与CD43无关的结合，在胸腺细胞上结合水平较低，而在CD4 T细胞、B细胞或骨髓细胞上未检测到结合。来自CD43基因敲除小鼠和CD43基因正常小鼠的淋巴结CD8+ T细胞上1B11染色水平相当。我们试图鉴定CD8 T细胞上表达的与CD43无关的1B11靶点。先前的研究表明，用神经氨酸酶处理淋巴结细胞（LNC）可增强1B11与CD43基因正常小鼠LNC的结合；在CD43基因敲除小鼠的LNC中也观察到这种增强。我们发现，神经氨酸酶增强的1B11与CD43基因敲除小鼠LNC和EL4胸腺瘤细胞的结合与CD43无关，并且1B11检测到一个新靶点，其表观质量约为200 kDa，被鉴定为CD45RB的低唾液酸化形式，优先在外周CD8而非CD4 T细胞上表达。我们的数据还表明，1B11对CD43和CD45RB的识别受O-连接糖基化和唾液酸的影响不同。虽然1B11对活化T细胞上CD43的识别需要核心2 O-聚糖分支和唾液酸，但1B11对CD45的识别仅在没有核心2糖基化和唾液酸的情况下发生。
