Howard Brandon A, Sempowski Gregory D, Scearce Richard M, Liao Hua-Xin, Lee David M, Lam Gordon K, Chen Haiyen, Fadden Patrick, Haystead Timothy, Haynes Barton F
Departments of Medicine, Duke University Medical Center, Duke Human Vaccine Institute, Durham, North Carolina, USA.
Hybridoma (Larchmt). 2008 Apr;27(2):81-9. doi: 10.1089/hyb.2007.0553.
Human (h) CD7 is a 40 kDa single chain Ig superfamily molecule that is expressed on thymocytes, a major subunit of peripheral T cells, and most natural killer cells. Ligands for hCD7 include the epithelial cell-produced molecule, K-12, and galectin. Mice deficient in CD7 have been shown to be resistant to LPS-induced endotoxic shock syndromes. However, monoclonal antibodies (MAb) to mouse (m) CD7 have yet to be produced, nor is the distribution of mCD7 protein in mice known. We have raised a panel of three rat MAbs to mCD7 by immunizing rats with recombinant mCD7 protein. However, using Western blot and immunoprecipitation of tissue extracts from mouse thymus, spleen, liver, brain, lymph node and skin, these anti-mouse CD7 MAbs bound only to murine heat shock protein 60 (HSP-60) present both in wild-type (CD7+/+) and CD7-deficient (CD7-/-) mice. Epitope mapping of the sites on HSP-60 and recombinant mCD7 recognized by mCD7 MAbs demonstrated non-homologous amino acid sequence epitopes recognized by anti-CD7 MAbs on both proteins. These data demonstrated molecular mimicry of mCD7 with HSP-60, and leave open the question of surface expression of mCD7.
人（h）CD7是一种40 kDa的单链免疫球蛋白超家族分子，表达于胸腺细胞、外周T细胞的一个主要亚群以及大多数自然杀伤细胞上。hCD7的配体包括上皮细胞产生的分子K-12和半乳糖凝集素。已证明CD7缺陷型小鼠对脂多糖诱导的内毒素休克综合征具有抗性。然而，针对小鼠（m）CD7的单克隆抗体（MAb）尚未产生，且mCD7蛋白在小鼠体内的分布也不清楚。我们通过用重组mCD7蛋白免疫大鼠，制备了一组三种针对mCD7的大鼠MAb。然而，利用蛋白质印迹法和对小鼠胸腺、脾脏、肝脏、脑、淋巴结和皮肤组织提取物进行免疫沉淀，这些抗小鼠CD7的MAb仅与野生型（CD7+/+）和CD7缺陷型（CD7-/-）小鼠体内均存在的小鼠热休克蛋白60（HSP-60）结合。对HSP-60上以及重组mCD7上被mCD7 MAb识别的位点进行表位作图，结果表明两种蛋白上被抗CD7 MAb识别的氨基酸序列表位是非同源的。这些数据证明了mCD7与HSP-60之间存在分子模拟，同时也留下了mCD7表面表达的问题。
