Monocyte-derived CD1a+ dendritic cells generated in two different culture systems: immunophenotypic and functional comparison

Expression of dendritic cell phenotypic antigens in cervical lymph nodes of patients with hypopharyngeal and laryngeal carcinoma

BACKGROUND

The purpose of this study was to assess the presence of dendritic cell phenotypic antigens in the cervical lymph nodes of patients with hypopharyngeal and laryngeal carcinoma, and to assess the significance of such antigens in the tumour immune reaction.

METHODS

Immunohistochemical staining of cervical lymph nodes was performed using antibodies against cell surface markers such as S-100 protein and cluster of differentiation 1a and 83 glycoproteins. Two hundred and seventy-four cervical lymph nodes obtained at surgery from 37 patients with hypopharyngeal carcinoma and 31 patients with laryngeal carcinoma were thus evaluated.

RESULTS

The number of dendritic cells positive for each phenotypic antigen was significantly greater in non-metastatic lymph nodes than in metastatic lymph nodes. In the metastatic lymph nodes, cluster of differentiation 1a glycoprotein positive dendritic cells were predominantly detected in the cancer 'nest', whereas mature dendritic cells staining for cluster of differentiation 83 glycoprotein were prominent in the peritumour area. In the metastatic lymph nodes, in contrast to the cluster of differentiation 1a glycoprotein positive dendritic cells, the degree of infiltration of cluster of differentiation 83 glycoprotein positive dendritic cells was significantly higher in the peritumour area than in the cancer nest. There was a significant difference in survival status, comparing patients with different degrees of dendritic cell infiltration for each type of phenotypic antigen.

CONCLUSIONS

Dendritic cells may play different roles in tumour immunity against hypopharyngeal and laryngeal carcinoma. The phenotypic antigens of dendritic cells may thus constitute important indices with which to predict the prognosis of patients with hypopharyngeal and laryngeal carcinoma.

Th1 polarization of CD4+ T cells by Toll-like receptor 3-activated human microglia

Toll-like receptors (TLRs) are expressed by human microglia and translate environmental cues into distinct activation programs. We addressed the impact of TLR ligation on the capacity of human microglia to activate and polarize CD4 T cell responses. As microglia exist under distinct states of activation, we examined both ramified and ameboid microglia isolated from adult and fetal CNS, respectively. In vitro, ligation of TLR3 significantly increased major histocompatibility complex and costimulatory molecule expression on adult microglia and induced high levels of interferon-alpha, interleukin-12p40, and interleukin-23. TLR4 and, in particular, TLR2 had a more limited capacity to induce such responses. Coculturing allogeneic CD4 T cells with microglia preactivated with TLR3 did not increase T cell proliferation above basal levels but consistently led to elevated levels of interferon-gamma secretion and Th1 polarization. Fetal microglial TLR3 responses were comparable; in contrast, TLR2 and TLR4 decreased major histocompatibility complex class II expression on fetal cells and reduced CD4 T cell proliferation to levels below those found in untreated cocultures. All 3 TLRs induced comparable interleukin-6 secretion by microglia. Our findings illustrate how activation of human microglia via TLRs, particularly TLR3, can change the profile of local CNS immune responses by translating Th1 polarizing signals to CD4 T cells.

IFN-gamma negatively regulates CpG-induced IL-10 in bone marrow-derived dendritic cells

Dendritic cells (DCs) are important players in the regulation of Th1- and Th2-dominated immune responses. In these studies we showed that IFN-gamma, the key mediator of Th1 immunity, actively suppressed the production of IL-10 in murine DCs when activated with LPS or CpG. Our analysis revealed that both LPS and CpG induced IL-10 and IL-12 production but that the presence of IFN-gamma, in a dose-dependent manner, suppressed the production of IL-10 while enhancing that of IL-12. The observed inhibition of IL-10 production was independent of IL-12. Experiments performed with STAT-1 knockout mice demonstrated that the primary production of IL-12 induced by CpG was STAT-1 dependent, whereas the production of IL-10 was not. This finding was confirmed by the observation that CpG-induced IL-12 production could be inhibited by anti-IFN-beta Abs, whereas CpG-induced IL-10 production could not be inhibited. These data also demonstrated that the inhibitory effect of IFN-gamma on IL-10 expression was STAT-1 dependent and transcriptionally regulated. Thus, DCs respond to CpG by producing proinflammatory and anti-inflammatory cytokines such as IL-12 and IL-10, respectively, and IFN-gamma acts to not only enhance IL-12 but also to inhibit IL-10 production. The current data demonstrate a novel pathway for IFN-gamma-mediated immunoregulation and suggest that IFN-gamma-dependent suppression of IL-10 production by DCs may be involved in the antagonism between Th1 and Th2 patterns of immune reactivity.

Dendritic cell immunizations alone or combined with low doses of interleukin-2 induce specific immune responses in melanoma patients

Dendritic cell (DC)-based therapy has proved to be effective in patients with a variety of malignancies. However, an optimal immunization protocol using DCs and the best means for delivering antigens has not yet been described. In this study, 20 patients with malignant melanoma in stages III or IV were vaccinated with autologous DCs pulsed with a melanoma cell lysate, alone (n = 13) or in combination with low doses of subcutaneous (s.c.) interleukin (IL)-2 injections (n = 7), to assess toxicity, immunological and clinical responses. Monocyte-derived DCs were morphological, phenotypic and functionally characterized in vitro. Peripheral blood mononuclear cells (PBMC), harvested from patients either prior to and after the treatment, were analysed using enzyme-linked immunosorbent spot (ELISPOT). After vaccination, 50% of the patients tested (seven of 13) from the first group and (three of seven) from the second, showed an increase in interferon (IFN)-gamma production in response to allogeneic melanoma cell lines but not to controls. Four of five tested human leucocyte antigen (HLA)-A2(+) patients with anti-melanoma activity also showed specific T cell responses against peptides derived from melanoma-associated antigens. Delayed type IV hypersensitivity reaction (DTH) against melanoma cell lysate was observed in six of 13 patients from the group treated with DC vaccines only and four of seven from the group treated with the combination of DCs and IL-2. Significant correlations were found between DTH-positive responses against tumour lysate and both disease stability and post-vaccination survival on the stage IV patients. There were no toxicities associated with the vaccines or evidence of autoimmunity including vitiligo. Furthermore, no significant enhancement was observed as a result of combining DC vaccination with IL-2. Our data suggest that autologous DCs pulsed with tumour lysate may provide a standardized and widely applicable source of melanoma specific antigens for clinical use. It is safe and causes no significant side effects and has been demonstrated to be partially efficient at triggering effective anti-melanoma immunity.

Dexamethasone Induces IL-10-Producing Monocyte-Derived Dendritic Cells with Durable Immaturity

It is highly desirable that immature dendritic cells (DC) used for tolerance induction maintain steady immature state with predominant interleukin (IL)-10 production. In this study, we attempted to develop DC with durable immaturity and other tolerogenic features by using dexamethasone (Dex). We found DC derived from human monocytes in the presence of 10(-7) m Dex were negative for CD1a. Compared with control transduced DC (Ctrl-DC), Dex-DC expressed lower CD40, CD80 and CD86 but equivalent human leucocyte antigen-DR. Both immature Dex- and Ctrl-DC did not express CD83. Nevertheless, upon stimulation of lipopolysaccharide (LPS) or CD40 ligand, the expression of CD40, CD80, CD83 and CD86 was upregulated on Ctrl-DC but not on Dex-DC. The immaturity of Dex-DC was durable following Dex removal. Interestingly, Dex-DC maintained production of large amount of IL-10 and little IL-12 five days after Dex removed. Further study indicated that high-level IL-10 production by Dex-DC was associated with high-level phosphorylation of extracellular signal-regulated kinase (ERK) as blockade of this enzyme markedly attenuated IL-10 production. Furthermore, Dex-DC sustained the capability of high phosphorylation of ERK and IL-10 production 5 days after Dex removal. In addition, Dex-DC had significantly lower activity in stimulating T-cell proliferation. Neutralization of IL-10, to some extent, promoted DC maturation activated by LPS, as well as T-cell stimulatory activity of Dex-DC. The above findings suggest that IL-10-producing Dex-DC with durable immaturity are potentially useful for induction of immune tolerance.