Waeckerle-Men Ying, Scandella Elke, Uetz-Von Allmen Edith, Ludewig Burkhard, Gillessen Silke, Merkle Hans P, Gander Bruno, Groettrup Marcus
Research Department, Cantonal Hospital St. Gallen, CH-9007 St. Gallen, Switzerland.
J Immunol Methods. 2004 Apr;287(1-2):109-24. doi: 10.1016/j.jim.2004.01.010.
Dendritic cells (DC) are increasingly explored as cellular vaccines for tumor immunotherapy. In most reported DC-based cancer vaccine trials, DC have been pulsed with soluble tumor antigen-derived peptide ligands of MHC molecules. Considering that the half-life of peptide/MHC complexes on the cell surface is relatively short and that soluble exogenous protein antigens cannot be efficiently processed via the MHC class I-processing pathway, the current vaccination procedure is not optimal for the induction of strong T cell responses aiming at tumor rejection. Recently, we have shown that antigen presentation can be prolonged when synthetic peptides were encapsulated in biodegradable poly(D,L-lactide-co-glycolide) (PLGA) microspheres (MS) for uptake by DC. In the present study, we investigated the phenotypic and functional consequences of MS uptake by human monocyte-derived dendritic cells (MoDC) in vitro. We found that immature MoDC that were prepared in serum free media suitable for clinical application were able to phagocytose high numbers of MS, while matured MoDC showed a reduced capacity for phagocytosis of MS. The ingestion of MS did not change the cell surface expression of CD80, CD83, CD86 and HLA-DR of immature and mature DC, suggesting that MS uptake did not induce DC maturation but that maturation by cytokines or LPS was unaltered in the presence of MS. Furthermore, MS-loaded mature MoDC expressed normal levels of the chemokine receptor CCR7 and migrated as efficiently towards CCL19 or CCL21 as unloaded MoDC. DC viability and the secretion of TNF-alpha and IL-12 was not significantly changed by MS loading. Taken together, our data indicate that PLGA-MS loading has no negative effects on the pivotal properties of MoDC in vitro. It should therefore be feasible to further develop this antigen loading strategy for clinical use in immunotherapy against viral infections and tumors.
树突状细胞（DC）作为肿瘤免疫治疗的细胞疫苗正受到越来越多的研究。在大多数已报道的基于DC的癌症疫苗试验中，DC已被用MHC分子的可溶性肿瘤抗原衍生肽配体进行脉冲处理。考虑到细胞表面肽/MHC复合物的半衰期相对较短，且可溶性外源蛋白抗原不能通过MHC I类加工途径有效加工，当前的疫苗接种程序对于诱导旨在肿瘤排斥的强烈T细胞反应并非最佳。最近，我们已经表明，当合成肽被包裹在可生物降解的聚（D，L-丙交酯-共-乙交酯）（PLGA）微球（MS）中以供DC摄取时，抗原呈递可以延长。在本研究中，我们在体外研究了人单核细胞衍生树突状细胞（MoDC）摄取MS的表型和功能后果。我们发现，在适合临床应用的无血清培养基中制备的未成熟MoDC能够吞噬大量MS，而成熟的MoDC对MS的吞噬能力降低。MS的摄取并未改变未成熟和成熟DC的CD80、CD83、CD86和HLA-DR的细胞表面表达，这表明MS摄取并未诱导DC成熟，但在存在MS的情况下，细胞因子或LPS诱导的成熟未改变。此外，负载MS的成熟MoDC表达正常水平的趋化因子受体CCR7，并且与未负载的MoDC一样有效地向CCL19或CCL21迁移。MS负载对DC活力以及TNF-α和IL-12的分泌没有显著影响。综上所述，我们的数据表明PLGA-MS负载对体外MoDC的关键特性没有负面影响。因此，进一步开发这种抗原负载策略用于针对病毒感染和肿瘤的免疫治疗临床应用应该是可行的。
