Impaired cytokine production in whole blood cell cultures of patients with urological carcinomas

IFN-gamma and T-bet expression in human dendritic cells from normal donors and cancer patients is controlled through mechanisms involving ERK-1/2-dependent and IL-12-independent pathways

Dendritic cells (DC) play a major role in priming naive T cells and modulating the immune response. We have previously reported that bryostatin-1, a potent immune modulator with antitumor activity, activates monocytes and lymphocytes to produce cytokines. Studies have shown that tumor-bearing hosts have a Th1/Th2 cytokine pattern that is associated with decreased production of IFN-gamma. We investigated the expression of IFN-gamma in bryostatin-1-treated human DC. Bryostatin-1 induced both IFN-gamma and T-bet mRNA expression in a dose- and time-dependent manner. As little as 1 ng/ml bryostatin-1 induced IFN-gamma and T-bet transcripts within 3 h and protein at 12 h. Treatment of DC with cycloheximide revealed that bryostatin-1-induced T-bet expression requires de novo protein synthesis, but bryostatin-1-induced IFN-gamma expression is independent of protein synthesis. Furthermore, dexamethasone inhibits bryostatin-1-induced IFN-gamma mRNA expression but increases bryostatin-1-induced T-bet mRNA expression. Experiments with ERK-1/2 inhibitors demonstrated that bryostatin-1 induction of IFN- gamma and T-bet was ERK-dependent and IL-12-independent. Similar results were obtained from both normal donors and cancer patients. In summary, our results suggest that bryostatin-1-induced IFN-gamma expression is T-bet independent. They also suggest for the first time that IFN- gamma and T-bet can be induced in human DC through an ERK-dependent pathway. Bryostatin-1-induced IFN- gamma may play a crucial role in the initiation of the immune response, before specific recognition by T cells that could be beneficial in the treatment of cancer.

Effects of Morus alba leaf extract on the production of nitric oxide, prostaglandin E2 and cytokines in RAW264.7 macrophages

Morus alba leaf methanolic extract and its fractions (chloroform, butanol, and aqueous fractions) were found to inhibit NO production in LPS-activated RAW264.7 macrophages without an appreciable cytotoxic effect at concentration from 4 to 100 microg/ml. LPS-induced PGE2 production was significantly reduced only by butanol fraction. In addition, M. alba leaf extract and its fractions significantly decreased the production of TNF-alpha. These findings suggest that M. alba leaf extract seems to be able in suppressing inflammatory mediators. Moreover, the inhibitory activities on COX-2 and iNOS of its butanol fraction are warranted for further elucidation of active principles for development of new antiinflammatory agents.

Determination of the eicosanoid response to inflammatory stimuli in whole blood and its pharmacological modulation ex vivo

Recognition of pathogens by immune cells initiates the release of numerous signaling molecules, including cytokines and eicosanoids. Here, we describe a simple procedure by which eicosanoids such as prostaglandin E(2) (PGE(2)), leukotriene B(4) (LTB(4)) and thromboxane B(2) (TxB(2)) can be measured using commercial enzyme immunoassays (EIAs) in the supernatant of whole blood stimulated with inflammatory stimuli. This is illustrated for numerous stimuli. The kinetics by which lipopolysaccharide (LPS) induces cyclooxygenase (COX)-2 expression in this setup were determined by quantitative reverse transcription polymerase chain reaction (RT-PCR). The eicosanoid response of the blood of 160 healthy volunteers to 1 microg/ml LPS was measured. To determine whether the action of a drug in vivo is represented ex vivo in the eicosanoid response of blood, one volunteer took a standard dose of a number of commercially available cyclooxygenase inhibitors on different days and the eicosanoid response of his blood to LPS was determined before ingestion as well as 2 and 6 h afterwards. The efficacy of the different pharmaceuticals on cyclooxygenase but not lipoxygenase products or cytokines could be monitored ex vivo. Similarly, ex vivo eicosanoid release was measured in blood from 10 volunteers who had taken 50 mg flurbiprofen. The method described extends approaches for studying whole blood cytokine release to the lipid mediators formed from arachidonic acid. These important signaling molecules represent targets for pharmacological intervention, which can now be monitored in vitro, as well as ex vivo employing the same model. Furthermore, the assay could be used to characterize the immune status of patient groups or to monitor the course of disease.

A model of human whole blood lymphokine release for in vitro and ex vivo use

Endotoxin (lipopolysaccharide, LPS) inducible cytokine release by human whole blood is increasingly used to model inflammatory responses in vitro, to detect the presence of pyrogenic contaminations as well as to monitor disease states or immunomodulatory treatments ex vivo. However, the LPS-stimulated blood model primarily allows the assessment of monocyte responses. Here, a whole blood model was established which allows assessment of lymphocyte responses. Four different superantigens, namely staphylococcal enterotoxin A and B (SEA, SEB), toxic shock syndrome toxin-1 (TSST-1) or streptococcal exotoxin A (SPEA) were tested with respect to the induction of lymphokine release. All superantigens were capable of inducing significant amounts of the lymphokines interferon-gamma (IFNgamma), interleukin 2 (IL-2), IL-4, IL-5, IL-13 and tumor necrosis factor beta (TNFbeta) after 72 h of incubation. Concentration-dependencies and kinetics were determined. Blood from 160 healthy donors was used to assess the variability of SEB-inducible lymphokine release. Interindividual differences were more pronounced compared to LPS-inducible monokine release. However, the individual response was maintained when blood from six donors was tested once a week for 8 weeks, suggesting that the individual response represents a donor characteristic. The model appears to be suitable for the evaluation of immunomodulatory agents in vitro as well as ex vivo.

Advances in prostate cancer immunotherapy

Metastatic prostate cancer remains incurable. Harnessing the body's own immune system to control or eradicate tumours has long been an attractive concept. Only recently has the field of tumour immunology provided the basic science behind the mechanisms of tumour genesis, molecular basis of the recognition of tumour associated antigens and the interactions of the antigen-presenting cells with effector cells. This research has been translated into numerous clinical immunotherapy strategies, which have reached the oncology clinic and which should provide options for our patients.

Naturally occurring prostate cancer antigen-specific T cell responses of a Th1 phenotype can be detected in patients with prostate cancer

BACKGROUND

Cytotoxic T cells (CTL) are considered one of the primary effector cell populations in antitumor immunity. Recent studies, however, have demonstrated the critical importance of helper T cells (Th), specifically interferon gamma (IFN gamma)-secreting Th1 cells, either by supporting an appropriate CTL environment or by recruiting other effector cells. We evaluated whether patients with prostate cancer have naturally occurring Th-cell responses specific for two prostate cancer-associated antigens, prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP), and whether Th1-type responses to these antigens could be detected.

METHODS

Peripheral blood mononuclear cells (PBMC) were collected from 80 patients with prostate cancer and 20 male controls without prostate disease. Th-cell responses were evaluated by measuring antigen-specific proliferation. IFN gamma and IL-5 secretion in response to antigen stimulation was determined by enzyme-linked immunosorbent assay.

RESULTS

T cell proliferative responses specific for PSA and PAP could be detected in patients with prostate cancer. Six percent (5/80) of patients had T cell responses specific for PSA and 11% (9/80) for PAP. T cell responses specific for PSA were more prevalent in patients with metastatic disease (P = 0.02), whereas responses specific for PAP could be detected in patients irrespective of disease stage. IFN gamma-producing Th cells, specific for both PSA and PAP, could be identified in patients with prostate cancer.

CONCLUSIONS

Patients with prostate cancer can have detectable Th-cell responses specific for the prostate cancer-associated proteins PSA and PAP. The presence of antigen-specific Th1 immune responses in prostate cancer patients suggests that an immune environment capable of supporting antigen-specific CTL may exist in vivo. Prostate 47:222-229, 2001.

Human prostate cancer regulates generation and maturation of monocyte-derived dendritic cells

BACKGROUND

The progression of prostate cancer is accompanied by a marked suppression of the immune system, including the apoptotic death of dendritic cells (DC) responsible for the induction of antitumor immunity. In this study, we evaluated whether prostate cancer might inhibit DC generation and maturation in vitro.

METHODS

DC were generated from peripheral blood monocytes in the presence of the human prostate cell line LNCaP or nonmalignant cells, and characterized by light microscopy, FACScan analysis, and ability to stimulate T-cell proliferation.

RESULTS

Prostate cancer significantly inhibited the conversion of monocytes into DC, which was assessed by the expression of DC markers CD1a and CD83. These cells were weak stimulators of T-cell proliferation, suggesting that DC generated in the prostate cancer microenvironment are functionally inhibited.

CONCLUSIONS

Prostate cancer not only kills mature DC, but also inhibits their generation and maturation, resulting in decreased production of antigen-presenting cells and inhibition of their functional activity.

Immunotherapy of advanced prostate cancer: a phase I/II trial using Mycobacterium vaccae (SRL172)

OBJECTIVE

To assess whether a new heat-killed Mycobacterium vaccae preparation (SRL172), which enhances cell-mediated immunity and has been proposed for use as an immunotherapeutic agent against cancer, is safe in patients with advanced hormone-refractory prostate cancer, can stimulate desirable cytokine changes in these patients and modulate the progression of the disease.

PATIENTS AND METHODS

Ten patients were given SRL172 intradermally at regular intervals. The serum prostate specific antigen (PSA) level was used as a surrogate marker of response. The proportion of peripheral blood mononuclear cells (PBMC) secreting interleukin 2 (IL2), interferon gamma (IFNgamma) and interleukin 4 (IL4) was measured by flow cytometry (FACS) before and after vaccination to assess whether the treatment induced a Th2 (predominantly humoral) to Th1 (predominantly cell-mediated) switch.

RESULTS

There were no significant adverse events. In five patients the serum PSA declined during the trial and in two of these there was no concomitant change of therapy apart from vaccination with SRL172. Before vaccination with SRL172 patients had a low proportion of PBMC producing IFNgamma and IL2 (all 10) and a higher proportion secreting IL4 (all three tested), suggesting a predominantly Th2 cytokine profile. After vaccination the proportion of IL4 secreting PBMC fell in all three patients tested. The proportion of IL2 secreting PBMC increased in three patients whose PSA fell. The proportion of IFNgamma-secreting cells remained depressed in nine of 10 patients.

CONCLUSION

Two patients with advanced hormone-refractory prostate cancer had a PSA response to the vaccination with SRL172. The proportion of PBMC secreting IL2 is a potential marker of response to immunotherapy.

Selective suppression of cytokine secretion in whole blood cell cultures of patients with colorectal cancer

We have investigated the secretion of interferon alpha (IFN-alpha), IFN-gamma, interleukin-1alpha (IL-1alpha), IL-1beta, IL-2 and tumour necrosis factor alpha (TNF-alpha) in whole blood cell cultures (WBCCs) of colorectal cancer patients upon mitogen stimulation. Whereas the values for IL-1beta and TNF-alpha remained virtually unchanged in comparison with healthy control subjects, WBCCs of colorectal cancer patients secreted significantly lower amounts of IFN-alpha (P < 0.005), IFN-gamma (P < 0.0001), IL-1alpha (P < 0.0001) and IL-2 (P < 0.05). This reduction correlated with the progression of the disease. The total leucocyte and monocyte population were almost identical in both groups. In contrast, a dramatic depletion of lymphocytes was observed in colorectal cancer patients, which affected both lymphocyte counts (P < 0.0005) and their distribution (P < 0.0001). Our results suggest a selective suppression of cytokines in colorectal cancer patients that is related to tumour burden. Several mechanisms might account for this phenomenon, one of which might be lymphocyte depletion.

Tumour-derived, endocrine, exogenous and therapeutic factors differentially modulate cytokine secretion in whole blood cell culture

Following our previous results which showed that TGF-beta 1 suppressed the secretion of certain cytokines, we investigated the effects of different endogenous and exogenous factors on cytokine secretion in whole blood cell culture by using an enzyme-linked immunosorbent assay (ELISA) for measurement of cytokine concentrations. Several molecules including dexamethasone, noradrenaline (NA) and ethanol differentially inhibited mitogen-induced cytokine secretion. Dexamethasone and noradrenaline suppressed secretion of IL-2, IFN alpha, IFN gamma, TNF alpha, IL-1 alpha and IL-1 beta. beta-Endorphin and Leu-Enkephalin had no significant influence on cytokine secretion. Suppression of cytokine secretion by TGF-beta 1 was further intensified significantly and dose dependently by addition of noradrenaline. GM-CSF stimulated the secretion of IL-1 alpha, IL-1 beta and TNF gamma, but had no influence on the secretion of IL-2, IFN alpha and IFN gamma. G-CSF, IL-3 and SCF did not significantly influence secretion of all cytokines tested. Thus, endogenous and exogenous factors differentially influence cytokine secretion by immunocompetent cells.

An evaluation of the accuracy of four ELISA methods for measuring natural and recombinant human interferon-g

We describe an evaluation of four ELISA methods, including three commercial kits, for measuring recombinant and natural human interferon-g (hIFN-g). Using a panel of samples, including well-characterized reference standards, we compared relative quantification between assays, within assays and, where possible, the absolute accuracy of quantification as compared to other analytical methods. The four assays generated markedly different results; up to an almost 60-fold difference between the highest and lowest values for one sample. The differences between assays were not necessarily predictable. No single correction factor could be determined to correct results from one method to another across the panel of samples tested. We conclude that investigators should be diligent to revalidate commercial methods before depending on such methods and resultant data.

Alterations in T cells of cancer-bearers: whence specificity?

T cells of tumor-bearing mice and cancer patients have been reported to have altered signal-transduction machinery. These alterations have been implicated in immunological suppression. Here, Daniel Levey and Pramod Srivastava critically examine the evidence for these alterations in the context of the tumor specificity of immunological unresponsiveness in tumor-bearing hosts.

Selective suppression of cytokine secretion in patients with small-cell lung cancer

BACKGROUND

Whether or not cytokine secretion is impaired in patients with small-cell lung cancer (SCLC), is unknown. We therefore investigated whether cytokine secretion by immunocompetent cells may be suppressed in patients with SCLC.

PATIENTS AND METHODS

We determined cytokine secretion by lymphocytes and monocytes in whole blood cell cultures from 58 patients with SCLC, 95 patients with non-small-cell lung cancer (NSCLC), 10 patients with nonmalignant lung disease and from 44 normal healthy individuals by using an enzyme-linked immunosorbent assay (ELISA) specific for the different cytokines measured.

RESULTS

Compares to normal controls, immunocompetent cells from patients with SCLC secreted significantly lower amounts of IL-2, IFN alpha, and IFN gamma upon mitogen stimulation. TNF alpha-secretion was significantly reduced in SCLC extensive disease but not in SCLC limited disease. In contrast, secretion of IL-1 alpha and IL-1 beta was not reduced. In patients with NSCLC, secretion of IL-2 and IFN alpha was significantly reduced. Reduction of IFN gamma secretion was significant in metastasized NSCLC and marginally significant in localized NSCLC. Secretion of TNF alpha, IL-1 alpha and IL-1 beta was not impaired. In addition, cytokine secretion in SCLC patients substantially improved upon successful reduction of tumor load by chemotherapy but not upon ineffective chemotherapy. Furthermore, TGF beta 1 suppressed secretion of IL-2, IFN alpha, IFN gamma, TNF alpha but not of IL-1 alpha and IL-1 beta in whole blood cell cultures from healthy individuals.

CONCLUSIONS

Suppression of cytokine secretion in patients with SCLC was selective, dependent on tumor load, different from immunosuppression in NSCLC and seemed to be reconstituted upon reduction of tumor load. These results may suggest interactions between tumor cells and the immune system. TGF beta 1 secreted by SCLC cell lines induced the same selective cytokine suppression as that found in SCLC patients. However, whether or not tumor-derived TGF beta 1 is a factor inducing selective immunosuppression in SCLC patients is presently unclear.