Yamada A, Imai Y, Hoshino T, Kubo K
Department of Immunology, Kurume University School of Medicine, Fukuoka, Japan.
Cell Immunol. 1995 Dec;166(2):254-60. doi: 10.1006/cimm.1995.9972.
We previously reported that the immunohistochemically defined LFA-1 antigen (LFA-1-like antigen) was expressed on various exocrine tissues uninvolved with tumors in patients with malignant diseases using LFA-1 alpha-specific monoclonal antibodies (mAb) 2F12 and HVS6B6. In this study we investigated differences at the molecular level between LFA-1 on leukocytes and LFA-1-like antigen on MKN45.16, a subline derived from an adenocarcinoma line MKN45 that expresses a high amount of LFA-1-like antigen. LFA-1-like antigen was reactive to mAb 2F12 or HVS6B6, but not to any of the other five different LFA-1 alpha (CD11a)-specific or four LFA-1 beta (CD18)-specific mAb. mAb 2F12 immunoprecipitated a 200-kDa membrane protein (LFA-1-like antigen) from MKN45.16 cells, whereas it precipitated 180-kDa (LFA-1 alpha) and 95-kDa (LFA-1 beta) proteins from a monocytic cell line (THP-1) under both nonreducing and reducing conditions. The molecular difference was confirmed further by N-glycanase treatment of the immunoprecipitates. The isoelectric point of LFA-1-like antigen was 6.0, whereas those of LFA-1 alpha and LFA-1 beta were 6.0 and 4.7, respectively, by two-dimensional gel electrophoresis. Expression of LFA-1 alpha gene on MKN45.16 cells was not detected at the mRNA level by six different sets of LFA-1 alpha-specific oligonucleotides and reverse transcription-polymerase chain reaction. These results indicated that LFA-1-like antigen on an adenocarcinoma cell line was a distinct molecule from LFA-1 on leukocytes.
我们先前报道，使用LFA-1α特异性单克隆抗体（mAb）2F12和HVS6B6，免疫组织化学定义的LFA-1抗原（LFA-1样抗原）在恶性疾病患者中未受肿瘤累及的各种外分泌组织上表达。在本研究中，我们调查了白细胞上的LFA-1与MKN45.16上的LFA-1样抗原在分子水平上的差异，MKN45.16是源自表达大量LFA-1样抗原的腺癌系MKN45的一个亚系。LFA-1样抗原与mAb 2F12或HVS6B6反应，但不与其他五种不同的LFA-1α（CD11a）特异性或四种LFA-1β（CD18）特异性mAb中的任何一种反应。mAb 2F12在非还原和还原条件下均从MKN45.16细胞中免疫沉淀出一种200 kDa的膜蛋白（LFA-1样抗原），而从单核细胞系（THP-1）中沉淀出180 kDa（LFA-1α）和95 kDa（LFA-1β）蛋白。通过对免疫沉淀物进行N-糖苷酶处理进一步证实了分子差异。通过二维凝胶电泳，LFA-1样抗原的等电点为6.0，而LFA-1α和LFA-1β的等电点分别为6.0和4.7。通过六组不同的LFA-1α特异性寡核苷酸和逆转录-聚合酶链反应，在mRNA水平未检测到MKN45.16细胞上LFA-1α基因的表达。这些结果表明，腺癌细胞系上的LFA-1样抗原是一种与白细胞上的LFA-1不同的分子。
