Loss of T-cell receptor-CD3zeta and T-cell function in tumor-infiltrating lymphocytes but not in tumor-associated lymphocytes in ovarian carcinoma

Extracellular vesicles in pancreatic cancer immune escape: Emerging roles and mechanisms

Pancreatic cancer (PC) is the most lethal malignancy worldwide due to its delayed diagnosis and limited treatment options. Despite great progress in clinical trials of immunotherapies for various cancers, their effectiveness in PC is very low, indicating that immune evasion is still a major obstacle to immunotherapy in PC. However, the mechanism of immune escape in PC is not fully understood, which substantially restricts the development of immunotherapy. As an important component of intercellular communication networks, extracellular vesicles (EVs) have attracted increasing attention in relation to immune escape. This review aims to provide a better understanding of the roles of EVs in tumor immune escape and the potential to expand their application in cancer immunotherapy. The relationship between PC and the tumor immune microenvironment is briefly introduced. Then, the mechanism by which EVs are involved in immune regulation is summarized, and the latest progress in determining the role of EVs in regulating PC immune escape is highlighted.

Oncolytic herpesvirus expressing PD-L1 BiTE for cancer therapy: exploiting tumor immune suppression as an opportunity for targeted immunotherapy

BACKGROUND

Programmed death-ligand 1 (PD-L1) is an important immune checkpoint protein that can be regarded as a pan-cancer antigen expressed by multiple different cell types within the tumor. While antagonizing PD-L1 is well known to relieve PD-1/PD-L1-mediated T cell suppression, here we have combined this approach with an immunotherapy strategy to target T cell cytotoxicity directly toward PD-L1-expressing cells. We developed a bi-specific T cell engager (BiTE) crosslinking PD-L1 and CD3ε and demonstrated targeted cytotoxicity using a clinically relevant patient-derived ascites model. This approach represents an immunological 'volte-face' whereby a tumor immunological defense mechanism can be instantly transformed into an Achilles' heel for targeted immunotherapy.

METHODS

The PD-L1 targeting BiTE comprises an anti-PD-L1 single-chain variable fragment (scFv) or nanobody (NB) domain and an anti-CD3 scFv domain in a tandem repeat. The ability to activate T cell cytotoxicity toward PD-L1-expressing cells was established using human carcinoma cells and PD-L1-expressing human ('M2') macrophages in the presence of autologous T cells. Furthermore, we armed oncolytic herpes simplex virus-1 (oHSV-1) with PD-L1 BiTE and demonstrated successful delivery and targeted cytotoxicity in unpurified cultures of malignant ascites derived from different cancer patients.

RESULTS

PD-L1 BiTE crosslinks PD-L1-positive cells and CD3ε on T cells in a 'pseudo-synapse' and triggers T cell activation and release of proinflammatory cytokines such as interferon-gamma (IFN-γ), interferon gamma-induced protein 10 (IP-10) and tumour necrosis factor-α (TNF-α). Activation of endogenous T cells within ascites samples led to significant lysis of tumor cells and M2-like macrophages (CD11b+CD64+ and CD206+/CD163+). The survival of CD3+ T cells (which can also express PD-L1) was unaffected. Intriguingly, ascites fluid that appeared particularly immunosuppressive led to higher expression of PD-L1 on tumor cells, resulting in improved BiTE-mediated T cell activation.

CONCLUSIONS

The study reveals that PD-L1 BiTE is an effective immunotherapeutic approach to kill PD-L1-positive tumor cells and macrophages while leaving T cells unharmed. This approach activates endogenous T cells within malignant ascites, generates a proinflammatory response and eliminates cells promoting tumor progression. Using an oncolytic virus for local expression of PD-L1 BiTE also prevents 'on-target off-tumor' systemic toxicities and harnesses immunosuppressive protumor conditions to augment immunotherapy in immunologically 'cold' clinical cancers.

Antibody to CMRF35-Like Molecule 2, CD300e A Novel Biomarker Detected in Patients with Fulminant Type 1 Diabetes

Aims/Hypothesis

Fulminant type 1 diabetes (FT1D) is a distinct subtype of type 1 diabetes and is fatal without immediate diagnosis and treatment. At present, there are no biomarkers for early and predictive detection of FT1D.

Methods

First, we analyzed a total of 6 serum samples from 3 patients with FT1D (1 sample in the acute and 1 in the sub-acute phases from each patient) by seromic analysis. Second, titres of the antibody were measured by ELISA in sera from 30 patients with FT1D (both in the acute and sub-acute phases), 13 patients with FT1D in the chronic phase, 32 patients with autoimmune type 1 (type 1A) diabetes (T1AD), 30 patients with type 2 diabetes (T2D), 23 patients with autoimmune thyroid disease (AITD) and 31 healthy control subjects (HC).

Results

Seromic analysis revealed 9 antibodies which showed high signals from all 3 patients with FT1D in the acute phase. Among them, the titre of anti-CD300e antibody was significantly higher in FT1D patients in the acute phase than that in T1AD, T2D, AITD patients and HC, as determined by ELISA (P<0.01, respectively). The titre of anti-CD300e antibody was also higher in FT1D in the acute phase than that in the sub-acute phase (P = 0.0018, Wilcoxon signed-rank test). The titre of anti-LGALS3 antibody in FT1D patients in the acute phase did not differ from that in patients with FT1D in the sub-acute phase, T1AD, T2D, AITD and HC.

Conclusion/Interpretation

The titre of a novel antibody, anti-CD300e, was high in sera from patients with FT1D. This antibody might be a diagnostic marker and provide new insight into the pathogenesis of FT1D.

Extracellular 2'5'-oligoadenylate synthetase 2 mediates T-cell receptor CD3-ζ chain down-regulation via caspase-3 activation in oral cancer

Decreased expression of CD3-ζ chain, an adaptor protein associated with T-cell signalling, is well documented in patients with oral cancer, but the mechanistic justifications are fragmentary. Previous studies in patients with oral cancer have shown that decreased expression of CD3-ζ chain was associated with decreased responsiveness of T cells. Tumours are known to induce localized as well as systemic immune suppression. This study provides evidence that oral tumour-derived factors promote immune suppression by down-regulating CD3-ζ chain expression. 2'5'-Oligoadenylate synthetase 2 (OAS2) was identified by the proteomic approach and our results established a causative link between CD3-ζ chain down-regulation and OAS2 stimulation. The surrogate situation was established by over-expressing OAS2 in a HEK293 cell line and cell-free supernatant was collected. These supernatants when incubated with T cells resulted in down-regulation of CD3-ζ chain, which shows that the secreted OAS2 is capable of regulating CD3-ζ chain expression. Incubation of T cells with cell-free supernatants of oral tumours or recombinant human OAS2 (rh-OAS2) induced caspase-3 activation, which resulted in CD3-ζ chain down-regulation. Caspase-3 inhibition/down-regulation using pharmacological inhibitor or small interfering RNA restored down-regulated CD3-ζ chain expression in T cells induced by cell-free tumour supernatant or rh-OAS2. Collectively these results show that OAS2 leads to impairment in CD3-ζ chain expression, so offering an explanation that might be applicable to the CD3-ζ chain deficiency observed in cancer and diverse disease conditions.

Coexpressed Catalase Protects Chimeric Antigen Receptor-Redirected T Cells as well as Bystander Cells from Oxidative Stress-Induced Loss of Antitumor Activity

Treatment of cancer patients by adoptive T cell therapy has yielded promising results. In solid tumors, however, T cells encounter a hostile environment, in particular with increased inflammatory activity as a hallmark of the tumor milieu that goes along with abundant reactive oxygen species (ROS) that substantially impair antitumor activity. We present a strategy to render antitumor T cells more resilient toward ROS by coexpressing catalase along with a tumor specific chimeric Ag receptor (CAR) to increase their antioxidative capacity by metabolizing H2O2. In fact, T cells engineered with a bicistronic vector that concurrently expresses catalase, along with the CAR coexpressing catalase (CAR-CAT), performed superior over CAR T cells as they showed increased levels of intracellular catalase and had a reduced oxidative state with less ROS accumulation in both the basal state and upon activation while maintaining their antitumor activity despite high H2O2 levels. Moreover, CAR-CAT T cells exerted a substantial bystander protection of nontransfected immune effector cells as measured by CD3ζ chain expression in bystander T cells even in the presence of high H2O2 concentrations. Bystander NK cells, otherwise ROS sensitive, efficiently eliminate their K562 target cells under H2O2-induced oxidative stress when admixed with CAR-CAT T cells. This approach represents a novel means for protecting tumor-infiltrating cells from tumor-associated oxidative stress-mediated repression.

Defect in recruiting effector memory CD8+ T-cells in malignant pleural effusions compared to normal pleural fluid

Background

Malignant pleural effusions (MPE) are a common and fatal complication in cancers including lung or breast cancers, or malignant pleural mesothelioma (MPM). MPE animal models and immunotherapy trials in MPM patients previously suggested defects of the cellular immunity in MPE. However only few observational studies of the immune response were done in MPM patients, using questionable control groups (transudate…).

Methods

We compared T cell populations evaluated by flow cytometry from blood and pleural effusion of untreated patients with MPM (n = 58), pleural metastasis of adenocarcinoma (n = 30) or with benign pleural lesions associated with asbestos exposure (n = 23). Blood and pleural fluid were also obtained from healthy subjects, providing normal values for T cell populations.

Results

Blood CD4⁺ or CD8⁺ T cells percentages were similar in all groups of patients or healthy subjects. Whereas pleural fluid from healthy controls contained mainly CD8⁺ T cells, benign or malignant pleural effusions included mainly CD4⁺ T cells. Effector memory T cells were the main T cell subpopulation in pleural fluid from healthy subjects. In contrast, there was a striking and selective recruitment of central memory CD4+ T cells in MPE, but not of effector cells CD8⁺ T cells or NK cells in the pleural fluid as one would expect in order to obtain an efficient immune response.

Conclusions

Comparing for the first time MPE to pleural fluid from healthy subjects, we found a local defect in recruiting effector CD8⁺ T cells, which may be involved in the escape of tumor cells from immune response. Further studies are needed to characterize which subtypes of effector CD8+ T cells are involved, opening prospects for cell therapy in MPE and MPM.

Chimeric NKG2D CAR-expressing T cell-mediated attack of human ovarian cancer is enhanced by histone deacetylase inhibition

NKG2D ligands (NKG2DLs) are widely expressed on ovarian cancers to various degrees, making them attractive targets for immunotherapy. Here, we applied a chimeric antigen receptor (CAR) approach for the targeting of NKG2DLs expressed on human ovarian cancer cells and evaluated the impact of pharmacological upregulation of NKG2DLs on immune recognition. Various NKG2DLs, including MICA/B and ULBP-1, -2, -3, and -4, were expressed at various levels on the surface of all established ovarian cancer cell lines and primary ovarian cancer samples tested. To redirect human T cells against NKG2DLs, an NKG2DL-specific CAR was generated by fusing the extracellular domain of the NKG2D receptor to the 4-1BB costimulatory and CD3-ζ chain signaling domains. In vitro expansion of chimeric NKG2D CAR T cells was delayed compared with untransduced T cells and control CAR T cells; the likely result of fratricide among activated T cells expressing NKG2DLs. However, NKG2D CAR T cells did expand and were selectively enriched during prolonged culture. In coculture, CD4(+) and CD8(+) NKG2D CAR T cells specifically recognized and killed NKG2DL-expressing ovarian cancer cell lines but not NKG2DL-negative cells. Notably, pretreatment of ovarian cancer cells expressing moderate to low levels of NKG2DLs with the histone deacetylase inhibitor sodium valproate (VPA) upregulated NKG2DL cell surface expression and consequently enhanced their immune recognition by chimeric NKG2D CAR T cells. Our results demonstrate that VPA-induced upregulation of NKG2DL expression enhances the immune recognition of ovarian cancer cells by engineered NKG2D CAR T cells, and rationalizes the use of VPA in combination with NKG2DL-targeted immunotherapy in ovarian cancer.

JAK3, STAT3 and CD3-zeta signaling proteins status in regard to the lymphocytes function in patients with ovarian cancer

Several groups of author have published that, in most cases of carcinoma, circulating lymphocytes are unable to carry out immune functions successfully. A molecular mechanism responsible for T lymphocytes defective reactivity in cancer patients is not completely defined. We evaluated whether the impaired function of peripheral blood lymphocytes (PBLs) from ovarian cancer patients could be associated with signaling elements such as JAK3, STAT3 and CD3-zeta chain. The study addressed to the simultaneous expression and phosphorylation status of mentioned molecules evaluation in regard to lymphocyte function in patients with advanced ovarian cancer has not yet been demonstrated by others. We found that PBLs of cancer patients showed lower JAK3, CD3-zeta molecules expression levels, as well as lower STAT3 and CD3-zeta phosphorylation levels than cells of control. The lower proliferative response and IL-2 production capacity of cancer patients PBLs in comparison with that of the control group cells were the functional consequences of reported in this study signaling abnormalities.

Suppression of T-cell expansion by melanoma is exerted on resting cells

BACKGROUND

Immunotherapeutic cancer protocols often rely on the ability to promote proliferative expansion of tumor-specific T-cell, but the influence of cancer on in vivo T-cell expansion remains largely undefined.

METHODS

The ability of control and B16F10 melanoma-bearing C57BL/6 mice to expand lymphocytic choriomeningitis virus antigen-specific T-cell populations in response to acute viral infection was compared by using flow cytometric assays of splenocytes.

RESULTS

The ability to expand virus-specific CD8+ and CD4+ T-cells was globally and markedly suppressed in tumor-bearing mice. Expanded cytotoxic T lymphocytes (CTLs) retained in vivo and in vitro functionality, suggesting that melanoma growth did not induce T-cell anergy. The magnitude of suppressed proliferative expansion was proportional to the extent of tumor burden. Melanoma-induced suppression of CTL expansion was correlated with upregulated apoptotic activity and hampered the induction of memory precursor effector cells. Adoptive transfer of resting LCMV antigen-specific T-cells before or after tumor establishment demonstrated that a critical period of in vivo exposure of resting T-cells to growing melanoma was responsible for the induction of suppressed expansion. This suppression was durable; surgical resection of melanoma after in vivo exposure to resting T-cells but before antigenic stimulation did not restore full expansion.

CONCLUSIONS

These data suggest that growing melanoma tumors exert a global, antigen-independent influence on resting T-cells that fundamentally reprograms their ability to undergo proliferative expansion in response to subsequent antigenic stimulation. This finding may have direct implications for T-cell-based immunotherapeutic strategies.

Tumor immunosuppressive environment: effects on tumor-specific and nontumor antigen immune responses

The interactions between cancer cells and host immune cells in tumoral microenvironments create an immunosuppressive network that promotes tumor growth, protects the tumor from immune attack and attenuates the efficacy of immunotherapeutic approaches. The development of immune tolerance becomes predominant in the immune system of patients with advanced-stage tumors. Several mechanisms have been described by which tumors can suppress the immune system, including secretion of cytokines, alterations in antigen-presenting cell subsets, costimulatory and coinhibitory molecule alterations and altered ratios of Tregs to effector T cells. It is well demonstrated that these mechanisms of immunosuppression can impair tumor specific immune responses. However, it is not well established whether this immunosuppressive environment can affect immune responses to nontumor antigens, specifically in regard to priming and the development of memory. The few existing studies indicate that responses to nontumor antigens seem unaffected, although there is still a deep lack of understanding of this phenomenon. This is an important issue regarding patient endurance and quality of life. Here, we review the existing evidence on immunosuppression promoted by tumors, with particular attention to its impact on specific immune responses. Understanding these interactions can help us subvert tumor-induced tolerance and optimize anti-tumor therapy.

The impact of T-cell immunity on ovarian cancer outcomes

Ovarian cancer remains a challenging disease for which improved treatments are urgently needed. Most patients present with advanced disease that is highly responsive to surgery combined with platinum- and taxane-based chemotherapy, with a state of minimal residual disease being achieved in many cases. However, chemotherapy-resistant recurrent tumors typically appear within 1-5 years and are ultimately fatal. Recently, several groups have shown that ovarian tumors are often infiltrated by activated T cells at the time of diagnosis, and patients with dense infiltrates of CD3+CD8+ T cells experience unexpectedly favorable progression-free and overall survival. Other cell types in the immune infiltrate oppose anti-tumor immunity, including CD4+CD25+FoxP3+ regulatory T cells, CD8+ regulatory T cells, macrophages, and dendritic cells. The composition of immune infiltrates is shaped by the expression of cytokines, chemokines, antigens, major histocompatibility complex molecules, and costimulatory molecules. The relationship between these various immunological factors is reviewed here with a strong emphasis on outcomes data so as to create a knowledge base that is well grounded in clinical reality. With improved understanding of the functional properties of natural CD8+ T-cell responses to ovarian cancer, there is great potential to improve clinical outcomes by amplifying host immunity.

Depressed and anxious mood and T-cell cytokine expressing populations in ovarian cancer patients

The adaptive immune response of ovarian cancer patients has been linked to survival, and is known to be impaired in the tumor microenvironment. Little is known about relationships between biobehavioral factors such as depressed mood and anxiety and the adaptive immune response in ovarian cancer. Thirty-seven patients with epithelial ovarian cancer and 14 patients with benign ovarian neoplasms completed psychosocial questionnaires pre-surgery. Lymphocytes from peripheral blood, tumor, and ascites (fluid around the tumor), were obtained on the day of surgery. Expression of the Type-1 cytokine interferon-gamma (IFN gamma), and the Type-2 cytokine interleukin-4 (IL-4) by T-helper (CD4(+)) and T-cytotoxic (CD8(+)) cells was measured under autologous tumor-stimulated, polyclonally-stimulated, or unstimulated conditions. Links with mood were examined. Among cancer patients, marked elevations in unstimulated and tumor-stimulated Type-2 responses were seen, particularly in ascites and tumor-infiltrating lymphocytes (P values<0.01). With polyclonal stimulation, lymphocytes from all compartments expressed elevated Type-1 cytokines (P values<0.014). Depressed and anxious mood were both associated with significantly lower ratios of polyclonally-stimulated CD4(+) cells producing IFN gamma (TH(1) cells) vs. IL-4 (TH(2) cells) in all compartments (depressed mood: P=0.012; anxiety: P=0.038) and depressed mood was also related to lower ratios of polyclonally-stimulated CD8(+) cells producing IFN gamma (TC(1)) vs. IL-4 (TC(2)) (P=0.035). Although effects of polyclonal stimulation should be generalized with caution to the in vivo immune response, findings suggest that depressed and anxious mood are associated with greater impairment of adaptive immunity in peripheral blood and in the tumor microenvironment among ovarian cancer patients.

Chimeric NKG2D Receptor–Bearing T Cells as Immunotherapy for Ovarian Cancer

Despite advancements in the treatment of ovarian cancer, this disease continues to be a leading cause of cancer death in women. Adoptive transfer of tumor-reactive T cells is a promising antitumor therapy for many cancers. We designed a chimeric receptor linking NKG2D, a natural killer (NK) cell-activating receptor, to the CD3zeta chain of the T-cell receptor to target ovarian tumor cells. Engagement of chimeric NKG2D receptors (chNKG2D) with ligands for NKG2D, which are commonly expressed on tumor cells, leads to T-cell secretion of proinflammatory cytokines and tumor cytotoxicity. In this study, we show that >80% of primary human ovarian cancer samples expressed ligands for NKG2D on the cell surface. The tumor samples expressed MHC class I-related protein A, MICB, and UL-16 binding proteins 1 and 3. ChNKG2D-expressing T cells lysed ovarian cancer cell lines. We show that T cells from ovarian cancer patients that express chNKG2D secreted proinflammatory cytokines when cultured with autologous tumor cells. In addition, we show that chNKG2D T cells can be used therapeutically in a murine model of ovarian cancer. These data indicate that treatment with chNKG2D-expressing T cells is a potential immunotherapy for ovarian cancer.

Cancer immunoediting from immune surveillance to immune escape

Cancer immune surveillance is considered to be an important host protection process to inhibit carcinogenesis and to maintain cellular homeostasis. In the interaction of host and tumour cells, three essential phases have been proposed: elimination, equilibrium and escape, which are designated the 'three E's'. Several immune effector cells and secreted cytokines play a critical role in pursuing each process. Nascent transformed cells can initially be eliminated by an innate immune response such as by natural killer cells. During tumour progression, even though an adaptive immune response can be provoked by antigen-specific T cells, immune selection produces tumour cell variants that lose major histocompatibility complex class I and II antigens and decreases amounts of tumour antigens in the equilibrium phase. Furthermore, tumour-derived soluble factors facilitate the escape from immune attack, allowing progression and metastasis. In this review, the central roles of effector cells and cytokines in tumour immunity, and the escape mechanisms of tumour cells during tumour progression are discussed.

Cancer immunoediting from immune surveillance to immune escape

Cancer immune surveillance is considered to be an important host protection process to inhibit carcinogenesis and to maintain cellular homeostasis. In the interaction of host and tumour cells, three essential phases have been proposed: elimination, equilibrium and escape, which are designated the 'three E's'. Several immune effector cells and secreted cytokines play a critical role in pursuing each process. Nascent transformed cells can initially be eliminated by an innate immune response such as by natural killer cells. During tumour progression, even though an adaptive immune response can be provoked by antigen-specific T cells, immune selection produces tumour cell variants that lose major histocompatibility complex class I and II antigens and decreases amounts of tumour antigens in the equilibrium phase. Furthermore, tumour-derived soluble factors facilitate the escape from immune attack, allowing progression and metastasis. In this review, the central roles of effector cells and cytokines in tumour immunity, and the escape mechanisms of tumour cells during tumour progression are discussed.

Expression of CD45 and proliferative response to CD3 as suitable classification markers of patients with gastric adenocarcinoma

25 patients with resectable gastric adenocarcinoma, subdivided according to the absence or presence of residual neoplasic disease (RND- or RND+, respectively), were studied. Cytofluorometric analysis and proliferative responses to mitogens was performed in peripheral blood mononuclear cells of patients. When compared to healthy subjects, the percentage of CD3-expressing cells was significantly reduced in both groups of patients studied (p < 0.0001 in all instances). However, when CD45 is considered instead of (CD3, its expression is found to be significantly reduced only in the RND+ patients (72% +/- 11), when compared with the control group (96 +/- 1%, p < 0.0001). Likewise, cells from these patients significantly less proliferated when stimulated with monoclonal antibodies to CD3 than control cells (18,920 +/- 6,019 cpm vs. 42,697 +/- 1,798 cpm, p = 0.0036); a difference not found if RND- patients (33,619 +/- 11,733 cpm) were considered. We propose that the low expression of CD45 and the poor response to CD3 are markers that are able to identify the subgroup of patients in whom the disease will tend to progress more rapidly. We also suggest the use of such markers as additional criteria for the classification of patients with gastric adenocarcinoma or to identify patients who require more aggressive therapeutic strategies.

Inhibition of lymphokine-activated killer cells generation in vitro by soluble factors released from mixed human tumor and peripheral blood mononuclear adherent cells culture

BACKGROUND

A variety of molecules produced by both tumor cells and normal cells reduce the activity of lymphokine-activated killer (LAK) cells. We tested the possible cross-regulation of mel-624 melanoma cells and adherent peripheral blood mononuclear cells (PBMCs) in affecting LAK cell activity.

METHODS

PBMC adherent cells were cultured together with mel-624 melanoma cells. Supernatant was transferred to a 4-day LAK cells generation culture consisted of PBMC nonadherent cells and interleukin-2. LAK cytotoxic activity was tested in a 4-hour assay against Daudi tumor cells prelabeled with sodium (51)chromate.

RESULTS

The supernatant produced within the first 48 hours of mixed mel-624 melanoma cell and adherent PBMC culture substantially (by 69 percent) reduced the generation of LAK cells, whereas the supernatant from either tumor culture or adherent PBMC culture had no effect. The inhibitory effect was manifested on the generation of LAK cells when autologous nonadherent cells were cultured with 1,000 units/ml IL-2, but there was no effect on mature LAK cell cytotoxic activity. Inhibition of LAK cell generation was partially dependent on protein synthesis and was not mediated by transforming growth factor ss (TGF-ss).

CONCLUSION

Our results point toward the production of soluble, yet unidentified proteins, in mixed tumor-adherent PBMC cultures, which substantially reduced the induction of LAK cells in culture.

Defective CD3ζ chain expression in Herpesvirus saimiri (HVS)-derived T-cell lines in gastric adenocarcinoma

Low expression of the CD3zeta chain has been reported in patients with cancer and it has been suggested that tumor-derived factors are involved in its downregulation. The expression of CD3zeta chain was measured in T-cell lines from patients with gastric adenocarcinoma and healthy volunteers and grown in vitro for several months and, hence, in the absence of any tumor-derived factors. T-cell lines of mucosal origin were obtained by Herpesvirus saimiri transformation from gastric cancer patients. The expression of CD3zeta and CD3epsilon was measured by flow cytometry and Western-blot analysis. Calcium mobilization and apoptosis rate were also measured. The levels of CD3zeta, but not CD3epsilon, chain on the cell surface were significantly reduced in T-cell lines derived from patients with gastric cancer when cultured in the absence of IL-2. Western-blot analysis of total cell extracts or lipid raft fractions confirmed this finding. Calcium mobilization, a measure of signal transduction, was reduced in T cell lines from patients with gastric cancer. We conclude that T cells from patients with cancer express lower levels of CD3zeta. This downregulation is not caused by a direct effect of tumor-derived factors but, rather, it appears to be inherent to the patient cells. The low CD3zeta expression would render T lymphocytes unable to control the growth of tumor cells.

Characterization of effusion-infiltrating T cells: benign versus malignant effusions

PURPOSE

While naïve T cells circulate between peripheral blood and lymph nodes, memory effector T cells acquire certain surface molecules that enable them to travel to peripheral tissues and exert their effector function. We analyzed whether deficient numbers of effector-type T cells within the malignant effusion might contribute to tumor escape from immunosurveillance.

EXPERIMENTAL DESIGN

We analyzed the expression of a broad range of adhesion molecules and chemokine receptors (CD62L, CD56, CCR4, CCR5, CCR7, CXCR3, CLA, and integrin alpha 4 beta 7) on tumor-associated lymphocytes in effusions and peripheral blood lymphocytes of patients with malignant ascites (n = 11) or malignant pleural effusion (n = 16). A tumor-associated lymphocyte:peripheral blood lymphocyte ratio was calculated as an indicator for homing of lymphocytes into the effusions and was compared with patients with nonmalignant ascites (n = 17).

RESULTS

Patients with malignancies show an increased enrichment of T cells expressing the phenotype of "naïve" (CD62L+ and CD45RA+CCR7+), "central memory" (CD45RA-CCR7+), and type 2-polarized (CCR4+) T cells within their effusions. In contrast, enrichment of "effector"-type (CD45RA-CCR7- or CD45RA+CCR7-) and presumably type 1-polarized T cells (CCR5+) at the tumor site is deficient. The same is true for natural killer cells and potentially cytotoxic CD56+ T cells.

CONCLUSIONS

Here we show for the first time that patients with malignant effusions show a deficient enrichment of T cells expressing the phenotype of type-1-polarized effector T cells at the tumor site. This mechanism is likely to contribute to the escape of tumor cells from immunosurveillance.

Immunophenotyping of tumor-infiltrating mononuclear cells in ovarian carcinoma

Infiltrating mononuclear cells play an important role in many types of cancer. The aim of this work was to determine the immunologic characteristics of mononuclear cellular infiltrate in ovarian cancer as compared to benign ovarian tumors. Paraffin-embedded tissues obtained from 52 ovarian carcinomas and 21 benign ovarian neoplasms were examined immunohistochemically to demonstrate suppressor/cytotoxic T cells and macrophages by using CD8 and CD68 monoclonal antibodies, respectively. The mean percentage of CD8+ cells was much higher in the malignant than in the benign group (P=0.00009). Similarly, the mean level of CD68+ cells was significantly higher in carcinomas than in benign cases (P=0.006). There was a significant negative correlation between the percentage of CD8+ cells and CD68+ cells in the malignant group (P=0.000002). Conversely, no correlation could be obtained between the values of these two cell types in the benign lesions. In the malignant group, although the percentages of CD8+ cells and CD68+ cells were not related to tumor differentiation, they were significantly related to tumor type. CD8+ cells were significantly higher in the serous (P=0.02), and CD68+ cells were higher in the mucinous carcinomas (P=0.0005). CD8+ T cells and macrophages constitute a major component of the infiltrating mononuclear cells in ovarian carcinoma. Their frequency seems to be related to the tumor type rather than the degree of tumor differentiation.

Ovarian carcinoma cells inhibit T cell proliferation: suppression of IL-2 receptor beta and gamma expression and their JAK-STAT signaling pathway

Deficient T cell immune function and intracellular signaling in cancer patients may result from effects of tumors or their products on lymphocytes. Recently, it was demonstrated that several ovarian carcinoma cell lines could produce soluble factors that inhibited T cell proliferation. The aim of this study is to assess the effect of supernatants from 3 ovarian carcinoma cell lines (OVCAR3, CAOV3, SKOV3) on signal transduction elements that are linked to the IL-2R and its JAK-STAT pathway. A profound inhibition of proliferation, lower level of IFN-gamma and higher level of IL-10 gene expression were observed when CD8+ T cells were co-cultured with supernatants from 3 ovarian carcinoma cell lines. Cell cycle studies on inhibited CD8+ T cells showed most of them were growth arrested in G0/G1 phase. Western blot analysis showed that tumor supernatants suppressed expression of JAK3 and tyrosine phosphorylation of STAT5. JAK1 was not altered and the inhibition of STAT3 only appeared in OVCAR3 cells. Tumor supernatants also partially blocked induction of IL-2R beta and gamma chains expression. These findings suggest that ovarian carcinoma cells may suppress T cell proliferation through inhibition IL-2 dependent signaling pathways, which may be a mechanism of ovarian carcinoma induced immunosuppression.

Decreased expression of the CD3zeta chain in T cells infiltrating the synovial membrane of patients with osteoarthritis

Osteoarthritis (OA) is a heterogeneous disease which rheumatologists consider to be noninflammatory. However, recent studies suggest that, at least in certain patients, OA is an inflammatory disease and that patients often exhibit inflammatory infiltrates in the synovial membranes (SMs) of macrophages and activated T cells expressing proinflammatory cytokines. We report here that the expression of CD3zeta is significantly decreased in T cells infiltrating the SMs of patients with OA. The CD3zeta chain is involved in the T-cell signal transduction cascade, which is initiated by the engagement of the T-cell antigen receptor and which culminates in T-cell activation. Double immunofluorescence of single-cell suspensions derived from the SMs from nine patients with OA revealed significantly increased proportions of CD3epsilon-positive (CD3epsilon+) cells compared with the proportions of CD3zeta-positive (CD3zeta+) T cells (means +/- standard errors of the means, 80.48% +/- 3.92% and 69.02% +/- 6.51%, respectively; P = 0.0096), whereas there were no differences in the proportions of these cells in peripheral blood mononuclear cells (PBMCs) from healthy donors (94.73% +/- 1.39% and 93.79% +/- 1.08%, respectively; not significant). The CD3zeta+ cell/CD3epsilon+ cell ratio was also significantly decreased for T cells from the SMs of patients with OA compared with that for T cells from the PBMCs of healthy donors (0.84 +/- 0.17 and 0.99 +/- 0.01, respectively; P = 0.0302). The proportions of CD3epsilon+ CD3zeta+ cells were lower in the SMs of patients with OA than in the PBMCs of healthy donors (65.04% +/- 6.7% and 90.81% +/- 1.99%, respectively; P = 0.0047). Substantial proportions (about 15%) of CD3epsilon+ CD3zeta-negative (CD3zeta-) and CD3epsilon-negative (CD3epsilon-) CD3zeta- cells were found in the SMs of patients with OA. Amplification of the CD3zeta and CD3delta transcripts from the SMs of patients with OA by reverse transcriptase PCR consistently exhibited stronger bands for CD3delta cDNA than for CD3zeta cDNA The CD3zeta/CD3delta transcript ratio in the SMs of patients with OA was significantly lower than that in PBMCs from healthy controls (P < 0.0001). These results were confirmed by competitive MIMIC PCR. Immunoreactivities for the CD3zeta protein were detected in the SMs of 10 of 19 patients with OA, and they were of various intensities, whereas SMs from all patients were CD3epsilon+ (P = 0.0023). The decreased expression of the CD3zeta transcript and protein in T cells from the SMs of patients with OA relative to that of the CD3epsilon transcript is suggestive of chronic T-cell stimulation and supports the concept of T-cell involvement in OA.