异基因树突细胞体外诱导抗慢性粒细胞白血病作用研究

树突细胞（DC）是体内惟一可以直接激活初始T细胞的专职抗原提呈细胞，是激发免疫应答的关键。我们选用持续表达BCR-ABL肿瘤抗原的K562细胞冻融抗原负载健康供者DC，避免自体肿瘤抗原和自身DC存在的缺陷，探索BCR-ABL肿瘤抗原负载的异基因健康供者DC在体外能否诱导HLA部分相合的慢性粒细胞白血病（CML）患者T细胞产生抗BCR-ABL^＋白血病效应。     

树突状细胞致敏的肿瘤疫苗对胰腺癌细胞的杀伤效应

目的:研究胰腺癌细胞冻融物致敏树突状细胞(DC)诱导的细胞毒性T细胞(CTL)对原代培养的自体胰腺癌细胞的杀伤作用．方法:从6例手术切除的胰腺癌组织中分离胰腺癌细胞,反复冻融获得肿瘤抗原;以该肿瘤抗原致敏外周血DC,诱导T细胞转变为CTL;采用Cr51释放法观察CTL对原代培养的自身胰腺癌细胞的杀伤活性,分别以来源于胰腺癌细胞株Pancl的肿瘤抗原致敏DC和未致敏DC刺激的CTL作为抗原对照和阴性对照．结果:实验组CTL对自身细胞的杀伤活性为69．05%±15．79%→88．05%±15．34％,抗原对照组CTL的杀伤活性为43．08％±6．92％→67．30％±8．91％,两组CTL杀伤率均显著高于阴性对照组(P<0．01);而实验组与抗原对照组相比,前者的杀伤活性显著高于后者者(P<0．05)．结论:胰腺癌细胞冻融物致敏的DC疫苗可以诱导T细胞产生高效的针对自体癌细胞的细胞毒效应;新鲜肿瘤组织来源的胰腺癌细胞比传代的Pancl细胞具有更好的抗原性．     

K562细胞可溶性抗原负载树突状细胞体外诱导CTL作用的研究

目的探讨经K562细胞裂解物冲击致敏的外周血单个核细胞衍生的树突状细胞（DC）的生物特性及体外诱导抗原特异性CTL应答的能力。方法采集健康人抗凝外周血分离单个核细胞，贴壁细胞用含rhGM—CSF、rhIL-4、TNF—α的RPM1640＋10％FBS培养基体外诱导培养产生DC，5天收获细胞并将细胞分组：A组：未负载抗原DC；B组：加入K562细胞裂解液脉冲DC。7天后用流式细胞仪检测成熟DC免疫表型，并将非贴壁细胞（淋巴细胞）作为效应细胞与各组DE共育，以产生细胞毒性T淋巴细胞（CTL）。12天用LDH释放试验测定对K562细胞的杀伤活性。并用ELISA方法测定细胞上清液中IL-12的含量。结果（1）经细胞因子联合体外诱导的各组DC较培养前在数量，形态及免疫表型上差异有统计学意义，CD86、CD83、CD40、CD1a表达增加，其中经K562细胞裂解液冲击的DC的CD83CD86表达率明显升高。（2）效应细胞与K562细胞混合培养时，负载K562细胞裂解液的DC刺激后的T细胞比单独DC刺激后的T细胞对K562细胞的杀伤作用更明显。（3）负载K562细胞裂解液的DC细胞培养上清液中产生IL-12含量较未负载抗原的DC明显增加。结论用GM—CSF、IL-4以及TNF—α诱导培养健康人外周血单个核细胞可以得到成熟的DC，且经K562细胞裂解液致敏可以进一步促进DC的成熟并体外诱导特异性杀伤靶细胞的CTL。     

树突状细胞与细胞因子诱导的杀伤细胞共培养对白血病耐药细胞杀伤作用的实验研究

目的探讨负载P-糖蛋白(P-gp)高表达的多药耐药(MDR)白血病K562/A02细胞冻融抗原的树突状细胞(DC)与同源细胞因子诱导的杀伤细胞(CIK)共培养对MDRK562/A02杀伤作用的影响。方法提取健康人骨髓单个核细胞,常规诱导出DC及CIK,将K562/A02细胞冻融物作为抗原冲击的DC,与CIK共培养作为实验组,抗原不冲击的DC与CIK共培养作为对照组,以CIK及DC单独培养分别作为空白对照组1和空白对照组2。光镜下观察细胞形态,流式细胞术分析细胞表型,MTT法检测杀伤活性。结果实验组、对照组细胞增殖活性均大于CIK组(P<0.05)。实验组对K562/A02、K562的杀伤活性在效靶比5∶1、10∶1、20∶1时分别为(42.90±0.67)%、(49.85±0.28)%、(63.36±0.46)%和(23.56±0.43)%、(26.11±0.34)%、(34.46±0.35)%,均高于对照组及空白对照组1(P<0.05);实验组对K562/A02的杀伤活性高于K562和MCF7(P<0.05)。结论DC与CIK共培养物是一种增殖活性和细胞毒活性高于CIK的免疫活性细胞,而经冻融抗原冲击的DC与CIK共培养能明显提高对MDRK562/A02的杀伤活性。     

肝癌干细胞抗原致敏的DC-CTL对肝癌的抑制作用

目的研究肝癌干细胞抗原致敏的树突细胞(DC)-细胞毒性T淋巴细胞(CTL)对裸鼠肝癌的抑瘤作用。方法肝细胞性肝癌患者手术后取肝癌组织,根据肝癌干细胞表面标志CD133,用磁珠分选法初步获得肝癌干细胞,反复冻融提取法获得肝癌干细胞抗原;采集同一患者外周血,加入细胞因子体外诱导、扩增抗原致敏的DC和细胞因子诱导的杀伤(CIK),从CIK中分选出CD3~+CD8~+T细胞;将肝癌干细胞抗原致敏的DC与CD3~+CD8~+T细胞共培养后,获得抗原致敏的DC-CTL细胞;制备裸鼠肝癌模型,动物实验观察抗原致敏的DC-CTL对裸鼠肝癌的抑瘤作用。结果肝癌干细胞抗原致敏的DC-CTL细胞和肝癌细胞抗原致敏的DC-CTL细胞对裸鼠肝癌均有极显著的抑制作用,两组间比较差异有统计学意义(P<0.05),肝癌干细胞抗原致敏组的抑瘤率明显增高。结论肝癌干细胞抗原致敏的DC-CTL对肝癌具有显著抑制作用。     

白血病抗原冲击致敏的树突状细胞诱导的抗肿瘤免疫反应

目的：研究树突状细胞(DC)的体外培养扩增及诱导特异性的抗肿瘤免疫反应。方法：使用mGM-CSF加mIL-4培养诱导骨髓细胞分化，采用反复冻融法制备L7212白血病细胞的冻融抗原(TAA)，在DC培养的第3天加入TAA，将TAA冲击致敏的DC与T淋巴细胞共培养，获得肿瘤特异性细胞毒性T淋巴细胞(CTL)，采用MTT法检测CTL对L7212细胞的杀伤作用及其对野生型L7212细胞再攻击的免疫保护作用。结果：MTT检测发现CTL对L7212细胞有特异性杀伤抑制作用，L7212抗原冲击致敏的DC能显著提高和延长野生型L7212细胞再攻击小鼠的生存率和存活期。结论：mGM-CSF和mIL-4配伍可有效地从小鼠骨髓细胞中诱导出大量的成熟的功能性DC，L7212白血病TAA冲击致敏的DC可诱导机体产生较强的抗肿瘤免疫反应。     

骨髓瘤独特型抗原负载树突细胞介导的抗肿瘤效应研究

目的:研究骨髓瘤独特型抗原(Idiotype,Id)负载树突细胞(DC)对同源细胞因子诱导的杀伤细胞(CIK)体外抗瘤活性的影响。方法:采集健康供者外周血单个核细胞(PBMNC)用常规方法诱导DC和CIK细胞,将骨髓瘤OPM-2细胞培养上清提取的Id冲击或未冲击的DC与CIK细胞共培养(CIK、DC加CIK、Id-DC加CIK),用流式细胞术分析细胞表型,MTT法检测体外效应细胞杀伤活性。结果:在(5～20):1效靶比范围内, CIK细胞对OPM-2和K562细胞的杀伤率分别为(24．47±3．00)％～(40．64±1．62)％和(23．36±1．51)％～(42．52±2．06)％。DC加CIK及Id—DC加CIK对OPM-2和K562细胞的杀伤活性均高于CIK组,差异有统计学意义(P<0．05);而在相同效靶比之下,Id-DC加CIK对OPM-2细胞的杀伤活性最强,差异有统计学意义(P <0．05)。结论:CIK细胞对骨髓瘤细胞有强的杀伤活性,经Id负载的DC与CIK细胞共培养能进一步增强其特异性杀伤活性,对骨髓瘤可能有免疫治疗作用。     

不同肝癌细胞抗原致敏树突状细胞体外诱导CTL活性的研究

目的比较不同方法提取的肝癌细胞(SMMC-7721)抗原致敏树突状细胞(Dendritic cell DC)后,对特异性细胞毒性T细胞(CTL)的诱导作用。方法分离脐带血单个核细胞,加入重组粒细胞-巨噬细胞集落刺激因子(GM-CSF)和白细胞介素4(IL-4)诱导扩增出脐血DC;SMMC-7721细胞经反复冻融,直接超声破碎及热休克处理后再超声破碎细胞三种方法提取肿瘤抗原,然后分别致敏DC,以MTT法检测脐血DC诱导T细胞增殖及其特异性CTL杀伤活性。结果热休克处理后再超声破碎法提取的抗原致敏DC,能诱导更强的刺激T细胞增殖的能力,并且可以诱导更强的CTL活性。结论加热处理后再超声破碎细胞提取的肿瘤抗原致敏DC,在体外可诱导强大的抗肿瘤免疫保护效应。     

K562冻融抗原负载的树突状细胞诱导抗慢性粒细胞白血病的免疫效应

目的研究K562冻融抗原负载的健康供者来源的树突状细胞(DC)诱导细胞毒性T淋巴细胞(CTL)体外杀伤慢性粒细胞白血病(CML)细胞的毒性效应。方法利用健康供者外周血单个核细胞诱导分化为DC,采用反复冻融法从K562中提取的可溶性相关抗原负载DC;流式细胞学检测负载抗原前后DC表面分子表达的变化;ELISA法检测DC上清中IL-12和IFNγ的含量;混合淋巴细胞反应(MLR)测定DC体外刺激T细胞增殖的能力;乳酸脱氢酶法检测K562冻融抗原负载DC诱导的抗原特异性CTL对CML细胞的杀伤作用。结果与未经抗原负载的DC相比,经K562抗原负载的DC表面分子表达明显上调,CD1a(27·40±5·00)%、(15·40±2·34)%,CD80(61·35±5·35)%、(42·00±2·77)%,CD83(93·30±3·48)%、(25·15±4·02)%,CD86(85·25±4·39)%、(37·25±3·20)%,CD40(89·80±7·18)%、(35·95±4·06)%,HLA-DR(49·50±5·45)%、(17·15±3·61)%,DC分泌IL-12和诱导T细胞分泌IFNγ的能力增加(P<0·05),具有很强的刺激T细胞增殖能力,且刺激强度在24h最强,48h降低,冻融抗原负载DC后激活的CTL在体外对K562的杀伤率为77·35%,显著高于未经抗原负载的DC(P=0·001)。结论经K562细胞冻融抗原负载DC激活的CTL在体外具有更强的增殖能力和杀伤CML细胞的作用。     

负载胰腺癌抗原的树突状细胞疫苗诱导T淋巴细胞抗肿瘤效应的研究

培养树突状细胞(DC),反复冻融法裂解培养的负载胰腺癌细胞(PC-3),提取细胞抗原,致敏DC,获得负载胰腺癌抗原的DC疫苗后诱导特异性细胞毒性T淋巴细胞(CTL)的生成,MTT法检测CTL对不同肿瘤细胞的杀伤作用.发现负载PC-3细胞抗原的DC疫苗能诱导产生肿瘤特异性的CTL,其对PC-3细胞具有明显地杀伤效应,而对人乳腺癌细胞MCF-7、人肝癌细胞7721细胞杀伤作用弱.认为负载胰腺癌抗原的DC疫苗能够诱导高效而特异地CTT杀瘤活性,为将来DC疫苗在胰腺癌的免疫治疗中提供了实验依据.     

Alpha-type 1-polarized dendritic cells loaded with apoptotic allogeneic myeloma cell line induce strong CTL responses against autologous myeloma cells

To induce a potent cytotoxic T lymphocyte (CTL) response, various tumor antigens should be loaded onto dendritic cells (DCs). In multiple myeloma (MM), it is difficult to obtain a sufficient number of autologous tumor cells as a source of tumor antigens in the clinical setting. We investigated the feasibility of immunotherapy in patients with MM, using myeloma-specific CTLs generated in vitro by alpha-type 1-polarized DCs (αDC1s) loaded with the ultraviolet B-irradiated allogeneic myeloma cell line, ARH77. αDC1s significantly increased the expression of several costimulatory molecules without differences in loading with tumor antigens. αDC1s showed a high production of interleukin-12 during maturation and after subsequent stimulation with CD40L but were not significantly affected by loading tumor antigens. Myeloma-specific CTLs against autologous myeloma cells from MM patients were induced by αDC1s pulsed with apoptotic ARH77 cells. Our data indicate that autologous DCs loaded with an allogeneic myeloma cell line can generate potent myeloma-specific CTL responses against autologous myeloma cells and might provide a practical method for cellular immunotherapy in patients with MM.     

肝癌细胞裂解物致敏的树突状细胞瘤苗体外诱导特异性抗肝癌免疫

目的 探讨肝癌患者肿瘤细胞裂解物致敏的树突状细胞(DC)瘤苗体外诱导自体T淋巴细胞特异性抗肝癌免疫效应。 方法 从肝癌患者外周血单个核细胞中诱导D C,用重组人粒细胞-巨噬细胞集落刺激因子(rhGM-CSF)和白细胞介素-4(rhIL-4)刺激活化,经自体肝癌细胞裂解物致敏。用流式细胞仪检测D C细胞表面分子的表达,酶联免疫吸附法检测T淋巴细胞培养上清液中干扰素(I F N)γ和白细胞介索-12(IL-12)的含量,液体闪烁计数仪测定肝癌细胞裂解物致敏的D C刺激自体T淋巴细胞增殖效应,四甲基偶氮唑盐法检测肝癌细胞裂解物致敏D C诱导的细胞毒T淋巴细胞对自体肝癌细胞的特异性杀伤作用。 结果 肝癌细胞裂解物致敏的DC瘤苗可上调DC表面CD1 a、CD40、CD86和人类白细胞抗原-DR分子表达水平,其与T淋巴细胞共培养产生的IFN γ、IL-12的浓度明显高于未致敏的D C组(t值分别为2.30、2.14,P<0.05),肝癌细胞裂解物组(t值分别为14.01、15.40,P<0.01)和对照组(t值分别为14.85、16.87,P<0.01)。同时肝癌细胞裂解物致敏的瘤苗可明显诱导T淋巴细胞的增殖,其诱导的细胞毒性T淋巴细胞对自体肝癌细胞的杀伤率(81.72％±9.49％)显著高于对HepG2的杀伤率(49.37％±11.21％)和人鼻咽癌肿瘤细胞的杀伤率(17.14％±5.65％),P<0.01。 结论 肝癌细胞     

Tumor lysate-specific cytotoxic T lymphocytes in multiple myeloma: promising effector cells for immunotherapy

The idiotype protein, secreted by myeloma plasma cells, is a tumor-specific but weak antigen. Idiotype-based immunotherapy has been explored in myeloma patients with disappointing results. It is conceivable that myeloma cells contain a multitude of tumor antigens that can more effectively stimulate antitumor T cells. To explore the possibility of using whole myeloma cells as a source of tumor antigens for immunotherapy, the current study was undertaken to generate and examine the function of myeloma-specific cytotoxic T lymphocytes (CTLs) by using dendritic cells (DCs) pulsed with myeloma cell lysates as stimulating cells. After repeated stimulation, specific CTL lines, containing CD4(+) and CD8(+) T cells, were generated from myeloma patients. Our results show that these T cells not only recognized and lysed autologous myeloma protein-pulsed DCs, they also killed autologous primary myeloma cells. Occasionally, CTLs responded to autologous idiotype-pulsed DCs and to allogeneic primary myeloma cells. No cytolytic activity, however, was detected against autologous lymphocytes including B cells, suggesting that the T cells acted specifically against myeloma cells. Cytotoxicity against target cells was major histocompatibility complex class 1 and, to a lesser extent, class 2 restricted and was dependent mainly on the perforin-mediated pathway. CTLs secreted predominantly interferon-gamma and tumor necrosis factor-alpha on antigenic stimulation, indicating a type 1 T-cell subset. These findings represent the first demonstration that tumor cell lysate-primed CTLs kill only myeloma cells, not autologous lymphocytes. This provides a rationale for myeloma cell-based immunotherapy in multiple myeloma.     

Induction of specific CTL by MAGE-3/CEA peptide-pulsed dendritic cells from HLA-A2/A24<Superscript>+</Superscript> gastrointestinal cancer patients

PURPOSE: In this study, we aimed to investigate whether MAGE3/CEA peptide-pulsed dendritic cells could induce specific cytotoxic T lymphocytes (CTL). METHODS: In this pilot study, we selected 25 patients expressing MAGE-3-HLA-A2/A24 or CEA-HLA-A24. Patients' dendritic cells (DCs) were expanded in vitro in the presence of recombined-human granular macrophage colony stimulating factor (rhGM-CSF) and recombined-human interleukin 4 (rhIL-4), pulsed with MAGE-3/CEA (HLA-A2/A24) peptide. The cytolytic cells' activity, induced by peptide-pulsed DCs and unpurified T cells as effector cells, and with Mel526, 803, Raji, and K562 as target cells, were measured using LDH-releasing assay. RESULTS: DCs were obtained by in vitro expansion in all cases although DC harvest rates varied among different patients (7.1+/-3.2%). Compared with T-IL-2 (IL-2-induced T cells), T-DC-P - which resulted from T-IL-2 co-cultured with DCs pulsed by MAGE3 or CEA peptides - exhibited an increase in cytolytic activity against Mel526 (expressing MAGE-3-HLA-A2) and 803 (expressing CEA-HLA-A24) cell lines by about 25-30% ( P<0.01). In contrast, there was no significant difference between the activity against Raji and K562 cells, which are negative for both peptides. CONCLUSIONS: This study showed that combined usage of rhGM-CSF and rhIL-4 in vitro could expand DCs, and that the DCs pulsed with specific peptides could induce MAGE- and CEA-specific CTL responses. The DC-based vaccine may provide an important method for the immunological treatment of gastrointestinal cancers.     

Ex vivo induction of multiple myeloma-specific cytotoxic T lymphocytes

Multiple myeloma (MM) is an incurable plasma cell malignancy characterized by immunosuppression. In this study, we identified factors in patients' bone marrow (BM) sera inhibiting autologous anti-MM immunity and developed an ex vivo strategy for inducing MM-specific cytotoxic T lymphocytes (CTLs). We found that sera from BM of MM patients inhibited induction of dendritic cells (DCs), evidenced by both phenotype and only weak stimulation of T-cell proliferation. Anti-vascular endothelial growth factor (anti-VEGF) and/or anti-interleukin 6 (anti-IL-6) antibodies neutralized this inhibitory effect, confirming that VEGF and IL-6, at least in part, mediate immunosuppression in MM patients. To induce MM-specific CTLs ex vivo, immature DCs were generated by culture of adherent mononuclear cells in medium containing granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4 for 5 days and then cocultured with apoptotic MM bodies in the presence of tumor necrosis factor alpha (TNF-alpha) for 3 days to induce their maturation. Autologous BM or peripheral blood mononuclear cells were stimulated weekly with these DCs, and cytotoxicity was examined against the MM cells used to pulse DCs. DCs cultured with apoptotic bodies stimulated significantly greater T-cell proliferation (stimulation index [SI] = 23.2 at a T-DC ratio of 360:1) than T cells stimulated by MM cells only (SI = 5.6), DCs only (SI = 9.3), or MM lysate-pulsed DCs (SI = 13.5). These CTLs from MM patients demonstrated specific cytotoxicity (24.7% at the effector-target [E/T] ratio of 40:1) against autologous primary MM cells. These studies therefore show that CTLs from MM patients can recognize and lyse autologous tumor cells and provide the framework for novel immunotherapy to improve patient outcome in MM.     

Successful cross-presentation of allogeneic myeloma cells by autologous alpha-type 1-polarized dendritic cells as an effective tumor antigen in myeloma patients with matched monoclonal immunoglobulins

For wide application of a dendritic cell (DC) vaccination in myeloma patients, easily available tumor antigens should be developed. We investigated the feasibility of cellular immunotherapy using autologous alpha-type 1-polarized dendritic cells (αDC1s) loaded with apoptotic allogeneic myeloma cells, which could generate myeloma-specific cytotoxic T lymphocytes (CTLs) against autologous myeloma cells in myeloma patients. Monocyte-derived DCs were matured by adding the αDC1-polarizing cocktail (TNFα/IL-1β/IFN-α/IFN-γ/poly-I:C) and loaded with apoptotic allogeneic CD138(+) myeloma cells from other patients with matched monoclonal immunoglobulins as a tumor antigen. There were no differences in the phenotypic expression between αDC1s loaded with apoptotic autologous and allogeneic myeloma cells. Autologous αDC1s effectively took up apoptotic allogeneic myeloma cells from other patients with matched subtype. Myeloma-specific CTLs against autologous target cells were successfully induced by αDC1s loaded with allogeneic tumor antigen. The cross-presentation of apoptotic allogeneic myeloma cells to αDC1s could generate CTL responses between myeloma patients with individual matched monoclonal immunoglobulins. There was no difference in CTL responses between αDC1s loaded with autologous tumor antigen and allogeneic tumor antigen against targeting patient's myeloma cells. Our data indicate that autologous DCs loaded with allogeneic myeloma cells with matched immunoglobulin can generate potent myeloma-specific CTL responses against autologous myeloma cells and can be a highly feasible and effective method for cellular immunotherapy in myeloma patients.     

Tumour cell/dendritic cell fusions as a vaccination strategy for multiple myeloma

Multiple myeloma (MM) cells express certain tumour-associated antigens (TAAs) that could serve as targets for active-specific immunotherapy. The aim of the present study was to test the MM/dendritic cell (DC) fusion as a vaccination strategy. We fused MM cells with DC to generate fusion cells (FCs) and tested their antigen presenting cell (APC) function in mixed lymphocyte reactions and cytotoxicity assays. First, the HS Sultan and SK0-007 HAT sensitive human MM cell lines and DCs generated from peripheral blood of normal donors were fused in the presence of 50% polyethylene glycol to form FCs. Next, tumour cells freshly isolated from patients were similarly fused with autologous DCs to generate FCs. The FCs demonstrated a biphenotypic profile, confirmed both by flow-cytometry and dual immunofluorescence microscopy. These FCs induced MM-specific cytotoxicity. FCs, but not MM cells or DCs alone, were potent stimulators of autologous patient T cells. More importantly, FC-primed autologous peripheral blood mononuclear cells demonstrated major histocompatibility complex-restricted MM-specific cytolysis. These studies therefore demonstrated that MM/DC FC can trigger an autologous immune response to MM cells and formed the framework for a clinical trial currently underway.     

Induction of HM1.24 peptide-specific cytotoxic T lymphocytes by using peripheral-blood stem-cell harvests in patients with multiple myeloma

HM1.24 antigen is preferentially overexpressed in multiple myeloma (MM) cells but not in normal cells. To explore the potential of HM1.24 as a target for cellular immunotherapy, we selected 4 HM1.24-derived peptides that possess binding motifs for HLA-A2 or HLA-A24 by using 2 computer-based algorithms. The ability of these peptides to generate cytotoxic T lymphocytes (CTLs) was examined in 20 healthy donors and 6 patients with MM by a reverse immunologic approach. Dendritic cells (DCs) were induced from peripheral-blood mononuclear cells of healthy donors or peripheral-blood stem-cell (PBSC) harvests from patients with MM, and autologous CD8(+) T cells were stimulated with HM1.24 peptide-pulsed DCs. Both interferon-gamma-producing and cytotoxic responses were observed after stimulation with either HM1.24-126 or HM1.24-165 peptides in HLA-A2 or HLA-A24 individuals. The peptide-specific recognition of these CTLs was further confirmed by tetramer assay and cold target inhibition assay. Importantly, HM1.24-specific CTLs were also induced from PBSC harvests from patients with MM and these CTLs were able to kill MM cells in an HLA-restricted manner. These results indicate the existence of functional DCs and HM1.24-specific CTL precursors within PBSC harvests and provide the basis for cellular immunotherapy in combination with autologous PBSC transplantation in MM.     

Natural cytotoxicity to autologous antigen-pulsed dendritic cells in multiple myeloma

To analyse autologous lymphocyte cytolytic activities of potential importance for cell-based immunotherapy in multiple myeloma (MM), in vitro differentiated dendritic cells (DCs) loaded with patient-specific monoclonal immunoglobulin (mIg) were used as autologous target cellsin cytotoxicity assays. Effector populations consisted of purified natural killer (NK) cells (CD56+, CD3-) and T cells (CD3+). The MM patients' NK cells cultured in the presence of interleukin 2 (IL-2) showed pronounced cytotoxic activity towards autologous mature DCs. Autologous MM DC targets displayed similar susceptibility to NK cell lysis, compared with allogeneic control DC targets, despite high surface expression of self major histocompatibility complex (MHC) antigens. However, some degree of classic MHC class I-mediated negative regulation was implicated in the NK-DC interactions, as indicated by class I blocking experiments. NK-mediated lysis was also discerned towards primary autologous MM cells. The results indicated that the major effector mechanism was mediated through the perforin-granzyme exocytosis pathway. In conclusion, NK cells from MM patients displayed significant and consistent cytotoxicity towards autologous mature DCs, suggesting that innate immunity could be implicated in MM and may influence the outcome of the administration of tumour antigen-pulsed DCs in treatment trials.     

Dendritic cells are functionally defective in multiple myeloma: the role of interleukin-6

We studied concentration, phenotype, and function of peripheral blood (PB) dendritic cells (DCs) from patients with multiple myeloma (MM). The absolute number of circulating precursors of myeloid and plasmacytoid DCs was significantly lower in MM patients than in healthy subjects. After maturation, PBDCs from MM patients showed significantly lower expression of HLA-DR, CD40, and CD80 antigens and impaired induction of allogeneic T-cell proliferation compared with controls. Remarkably, they were not capable of presenting the patient-specific tumor idiotype to autologous T cells. Conversely, DCs generated in vitro from CD14(+) monocytes from the same patients, and PBDCs freshly isolated from healthy donors efficiently stimulated allogeneic and autologous T cells. To clarify the mechanism of PBDC deficiency in MM, we investigated the effects of the main plasma cell growth factor, interleukin-6 (IL-6), on the development of DCs from CD34(+) cells. IL-6 inhibited the colony growth of CD34(+) DC progenitors and switched the commitment of CD34(+) cells from DCs to CD14(+) CD1a(-) CD86(-)CD80(-) CD40(+/-)HLA-DR +/- monocytic cells exerting potent phagocytic activity but no antigen-presentation capacity. This effect was reversed by anti-IL-6 antibodies. Growing CD34(+) cells in the presence of autologous serum (without IL-6) also suppressed the development of functional DCs. This study demonstrates that PBDCs from MM patients are functionally defective, partially because of IL-6-mediated inhibition of development. This brings into question the advisability of using PBDCs as antigen carriers for immunotherapy trials in MM. The results also suggest a novel mechanism whereby myeloma cells escape immune recognition.