Sotomayor E M, Fu Y X, Lopez-Cepero M, Herbert L, Jimenez J J, Albarracin C, Lopez D M
Department of Microbiology and Immunology, University of Miami School of Medicine, FL 33101.
J Immunol. 1991 Oct 15;147(8):2816-23.
Peritoneal elicited macrophages (PEM) from mammary tumor-bearing mice have a decreased capacity to become cytotoxic against syngeneic, allogeneic, and xenogeneic target cells upon in vitro stimulation with LPS, as compared with PEM of normal mice. A regulatory mechanism other than PG release is suggested because the addition of both indomethacin and LPS to macrophage cultures from tumor-bearing mice caused no changes in their cytotoxic capability. Because tumor products have been implicated in the down-regulation of immune responses, we investigated whether pretreatment with supernatants from the tumor cell line DA-3, derived from the in vivo mammary adenocarcinoma D1-DMBA-3, affects the cytolytic capacity of macrophages. This treatment inhibits, in a dose-dependent fashion, the ability of stimulated normal PEM to kill target cells. Partial purification of DA-3 cell line supernatant showed that most of the inhibitory activity was exerted by factors with a molecular mass greater than 10 kDa and less than 30 kDa. However, slight inhibition could also be observed with fractions containing molecules less than 10 kDa. The data suggest that more than one factor released by the mammary tumor cells may be involved in the down-regulation of macrophage-mediated cytotoxicity. Because the DA-3 cells constitutively produce granulocyte-macrophage CSF (GM-CSF), which has a molecular mass of 27 kDa, we pretreated PEM from normal mice in vitro with rGM-CSF for 24 h. This resulted in a dose-dependent decrease in their capacity to kill tumor target cells upon LPS stimulation. Furthermore, PEM from normal mice injected with rGM-CSF for 25 days displayed a profound decrease in their cytolytic ability against DA-3 targets upon in vitro stimulation with increasing amounts of LPS. The pretreatment of PEM from normal mice with a combination of DA-3 cell supernatants and specific anti-GM-CSF partially neutralized the inhibitory effect of the DA-3 supernatant on macrophage tumoricidal capability. These results indicate that tumor-derived GM-CSF is an important factor involved in the decreased macrophage cytotoxicity during mammary adenocarcinoma progression.
与正常小鼠的腹腔诱导巨噬细胞（PEM）相比，来自患乳腺肿瘤小鼠的PEM在体外经脂多糖（LPS）刺激后，对同基因、异基因和异种靶细胞产生细胞毒性的能力降低。由于向来自荷瘤小鼠的巨噬细胞培养物中添加吲哚美辛和LPS后其细胞毒性能力没有变化，因此提示存在除前列腺素释放之外的调节机制。由于肿瘤产物与免疫反应的下调有关，我们研究了用源自体内乳腺腺癌D1-DMBA-3的肿瘤细胞系DA-3的上清液进行预处理是否会影响巨噬细胞的溶细胞能力。这种处理以剂量依赖的方式抑制了受刺激的正常PEM杀伤靶细胞的能力。对DA-3细胞系上清液进行部分纯化显示，大部分抑制活性由分子量大于10 kDa且小于30 kDa的因子发挥。然而，在含有小于10 kDa分子的组分中也可观察到轻微抑制。数据表明，乳腺肿瘤细胞释放的不止一种因子可能参与巨噬细胞介导的细胞毒性的下调。由于DA-3细胞组成性产生分子量为27 kDa的粒细胞-巨噬细胞集落刺激因子（GM-CSF），我们在体外用重组GM-CSF对正常小鼠的PEM预处理24小时。这导致它们在LPS刺激后杀伤肿瘤靶细胞的能力呈剂量依赖性下降。此外，用重组GM-CSF注射25天的正常小鼠的PEM在体外经越来越多的LPS刺激后，对DA-3靶标的溶细胞能力显著下降。用DA-3细胞上清液和特异性抗GM-CSF的组合对正常小鼠的PEM进行预处理，部分中和了DA-3上清液对巨噬细胞杀肿瘤能力的抑制作用。这些结果表明，肿瘤来源的GM-CSF是乳腺腺癌进展过程中巨噬细胞细胞毒性降低所涉及的一个重要因素。
