Strong HLA-DR expression in large bowel carcinomas is associated with good prognosis

MHC class II molecules on pancreatic cancer cells indicate a potential for neo-antigen-based immunotherapy

MHC class II expression is a hallmark of professional antigen-presenting cells and key to the induction of CD4+ T helper cells. We found that these molecules are ectopically expressed on tumor cells in a large proportion of patients with pancreatic ductal adenocarcinoma (PDAC) and on several PDAC cell lines. In contrast to the previous reports that tumoral expression of MHC-II in melanoma enabled tumor cells to evade immunosurveillance, the expression of MHC-II on PDAC cells neither protected cancer cells from Fas-mediated cell death nor caused T-cell suppression by engagement with its ligand LAG-3 on activated T-cells. In fact and surprisingly, the MHC-II/LAG-3 pathway contributed to CD4+ and CD8+ T-cell cytotoxicity toward MHC-II-positive PDAC cells. By combining bioinformatic tools and cell-based assays, we identified a number of immunogenic neo-antigens that can be presented by the patients' HLA class II alleles. Furthermore, CD4+ T-cells stimulated with neo-antigens were capable of recognizing and killing a human PDAC cell line expressing the mutated genes. To expand this approach to a larger number of PDAC patients, we show that co-treatment with IFN-γ and/or MEK/HDAC inhibitors induced tumoral MHC-II expression on MHC-II-negative tumors that are IFN-γ-resistant. Taken together, our data point to the possibility of harnessing MHC-II expression on PDAC cells for neo-antigen-based immunotherapy.

HLA-DR Presentation of the Tumor Antigen MSLN Associates with Clinical Outcome of Ovarian Cancer Patients

Simple Summary

The immunopeptidome represents the entirety of peptides that are presented on the surface of cells on human leukocyte antigen (HLA) molecules and are recognized by the T-cell receptors of CD4⁺ and CD8⁺ T-cells. Malignant cells present tumor-associated antigens essential for tumor immune surveillance, which can be targeted by T-cell-based immunotherapy approaches. For ovarian carcinomas, various tumor-associated antigens, such as Mucin-16 and Mesothelin, have been described. The aim of our study is to analyze immunopeptidome-defined tumor antigen presentation in ovarian carcinoma patients in relation to clinical characteristics and disease outcomes to define potential biomarkers. Our work demonstrates the central role of HLA-DR-restricted peptide presentation of the tumor antigen Mesothelin and of CD4⁺ T-cell responses for tumor immune surveillance, and underlines Mesothelin as a prime target antigen for novel immunotherapeutic approaches for ovarian carcinoma patients.

Abstract

T-cell recognition of HLA-presented antigens is central for the immunological surveillance of malignant disease and key for the development of novel T-cell-based immunotherapy approaches. In recent years, large-scale immunopeptidome studies identified naturally presented tumor-associated antigens for several malignancies. Regarding ovarian carcinoma (OvCa), Mucin-16 (MUC16) and Mesothelin (MSLN) were recently described as the top HLA class I- and HLA class II-presented tumor antigens, respectively. Here, we investigate the role and impact of immunopeptidome-presented tumor antigens on the clinical outcomes of 39 OvCa patients with a follow-up time of up to 50 months after surgery. Patients with a HLA-restricted presentation of high numbers of different MSLN-derived peptides on their tumors exhibited significantly prolonged progression-free (PFS) and overall survival (OS), whereas the presentation of MUC16-derived HLA class I-restricted peptides had no impact. Furthermore, a high HLA-DRB gene expression was associated with increased PFS and OS. In line, in silico prediction revealed that MSLN-derived HLA class II-presented peptides are predominantly presented on HLA-DR allotypes. In conclusion, the correlation of MSLN tumor antigen presentation and HLA-DRB gene expression with prolonged survival indicates a central role of CD4⁺ T-cell responses for tumor immune surveillance in OvCa, and highlights the importance of immunopeptidome-guided tumor antigen discovery.

Tumor Cells and the Extracellular Matrix Dictate the Pro-Tumoral Profile of Macrophages in CRC

Tumor-associated macrophages (TAMs) are major components of the tumor microenvironment. In colorectal cancer (CRC), a strong infiltration of TAMs is accompanied by a decrease in effector T cells and an increase in the metastatic potential of CRC. We investigated the functional profile of TAMs infiltrating CRC tissue by immunohistochemistry, flow cytometry, ELISA, and qRT-PCR and their involvement in impairing the activation of effector T cells. In CRC biopsies, we evidenced a high percentage of macrophages with low expression of the antigen-presenting complex MHC-II and high expression of CD206. Monocytes co-cultured with tumor cells or a decellularized tumor matrix differentiated toward a pro-tumoral macrophage phenotype characterized by decreased expression of MHC-II and CD86 and increased expression of CD206 and an abundant release of pro-tumoral cytokines and chemokines. We demonstrated that the hampered expression of MHC-II in macrophages is due to the downregulation of the MHC-II transactivator CIITA and that this effect relies on increased expression of miRNAs targeting CIITA. As a result, macrophages become unable to present antigens to CD4 T lymphocytes. Our data suggest that the tumor microenvironment contributes to defining a pro-tumoral profile of macrophages infiltrating CRC tissue with impaired capacity to activate T cell effector functions.

MHC heterogeneity and response of metastases to immunotherapy

In recent years, immunotherapy has proven to be an effective treatment against cancer. Cytotoxic T lymphocytes perform an important role in this anti-tumor immune response, recognizing cancer cells as foreign, through the presentation of tumor antigens by MHC class I molecules. However, tumors and metastases develop escape mechanisms for evading this immunosurveillance and may lose the expression of these polymorphic molecules to become invisible to cytotoxic T lymphocytes. In other situations, they may maintain MHC class I expression and promote immunosuppression of cytotoxic T lymphocytes. Therefore, the analysis of the expression of MHC class I molecules in tumors and metastases is important to elucidate these escape mechanisms. Moreover, it is necessary to determine the molecular mechanisms involved in these alterations to reverse them and recover the expression of MHC class I molecules on tumor cells. This review discusses the role and regulation of MHC class I expression in tumor progression. We focus on altered MHC class I phenotypes present in tumors and metastases, as well as the molecular mechanisms responsible for MHC-I alterations, emphasizing the mechanisms of recovery of the MHC class I molecules expression on cancer cells. The individualized study of the HLA class I phenotype of the tumor and the metastases of each patient will allow choosing the most appropriate immunotherapy treatment based on a personalized medicine.

Therapeutic applications of the selective high affinity ligand drug SH7139 extend beyond non-Hodgkin's lymphoma to many other types of solid cancers

SH7139, the first of a series of selective high affinity ligand (SHAL) oncology drug candidates designed to target and bind to the HLA-DR proteins overexpressed by B-cell lymphomas, has demonstrated exceptional efficacy in the treatment of Burkitt lymphoma xenografts in mice and a safety profile that may prove to be unprecedented for an oncology drug. The aim of this study was to determine how frequently the HLA-DRs targeted by SH7139 are expressed by different subtypes of non-Hodgkin’s lymphoma and by other solid cancers that have been reported to express HLA-DR. Binding studies conducted with SH7129, a biotinylated analog of SH7139, reveal that more than half of the biopsy sections obtained from patients with different types of non-Hodgkin’s lymphoma express the HLA-DRs targeted by SH7139. Similar analyses of tumor biopsy tissue obtained from patients diagnosed with eighteen other solid cancers show the majority of these tumors also express the HLA-DRs targeted by SH7139. Cervical, ovarian, colorectal and prostate cancers expressed the most HLA-DR. Only a few esophageal and head and neck tumors bound the diagnostic. Within an individual’s tumor, cell to cell differences in HLA-DR target expression varied by only 2 to 3-fold while the expression levels in tumors obtained from different patients varied as much as 10 to 100-fold. The high frequency with which SH7129 was observed to bind to these cancers suggests that many patients diagnosed with B-cell lymphomas, myelomas, and other non-hematological cancers should be considered potential candidates for new therapies such as SH7139 that target HLA-DR-expressing tumors.

Characterising the prognostic potential of HLA-DR during colorectal cancer development

HLA-DR, an MHC class II molecule that mediates antigen presentation, is a favourable prognostic indicator in colorectal cancer (CRC). However, the dynamics and location of HLA-DR expression during CRC development are unclear. We aimed to define HLA-DR expression by immunohistochemistry in colorectal epithelium and stromal tissue at different stages of cancer development, assessing non-neoplastic colorectal adenocarcinoma-adjacent tissue, adenomas and carcinoma tissues, and to associate HLA-DR levels with clinical outcomes. Patients with higher than median HLA-DR expression survived at least twice as long as patients with lower expression. This association was significant for HLA-DR staining in the colorectal carcinoma epithelium (n = 152, p = 0.011, HR 1.9, 95% CI 1.15-3.15) and adjacent non-neoplastic epithelium (n = 152, p < 0.001, HR 2.7, 95% CI 1.59-4.66), but not stroma. In stage II cases, however, the prognostic value of HLA-DR expression was significant only in adjacent non-neoplastic tissues, for both epithelium (n = 63, p = 0.015, HR 3.6, 95% CI 1.279-10.25) and stroma (n = 63, p = 0.018, HR 5.07, 95% CI 1.32-19.49). HLA-DR was lower in carcinoma tissue compared to matched adenomas (n = 35), in epithelium (p < 0.01) and stroma (p < 0.001). HLA-DR was further reduced in late-stage carcinoma (n = 101) compared to early stage (n = 105), in epithelium (p < 0.001) and stroma (p < 0.01). HLA-DR expression was lower (p < 0.05) in the adjacent non-neoplastic epithelium of patients with cancer recurrence. We demonstrate a progressive loss of HLA-DR in epithelial and stromal tissue compartments during CRC development and show prognostic ability in carcinoma-adjacent non-neoplastic tissues, highlighting the importance of this molecule in the anti-cancer immune response. These findings may have wider implications for immunotherapeutic interventions.

HLA Class-II Expression in Human Tumors

HLA class II molecules play a pivotal role in antigen presentation to T lymphocytes. This chapter analyzed the expression of these molecules in different human tumors and their role in cancer progression. The possible connection between tumor HLA class II expression and the pathogenesis of autoimmune diseases is discussed.

HLA-DR expression in tumor epithelium is an independent prognostic indicator in esophageal adenocarcinoma patients

Esophageal adenocarcinoma (EAC) is an aggressive cancer with poor prognosis, and incidence is increasing rapidly in the Western world. Measurement of immune markers has been shown to have prognostic significance in a growing number of cancers, but whether this is true for EAC has yet to be evaluated. This study aimed to characterize HLA-DR expression in the esophagus across the inflammation to cancer progression sequence and to assess the prognostic significance of HLA-DR expression in EAC. Tissue microarrays (TMA) were constructed from esophageal tissue taken from patients at different stages in the cancer progression sequence; normal, esophagitis, Barrett’s esophagus (BE), low- and high-grade dysplasia (LGD, HGD) and EAC. HLA-DR expression in tissue epithelium and stroma was assessed by immunohistochemistry. HLA-DR expression increased early in the inflammation to cancer progression sequence; with higher expression detected in esophagitis and BE compared to normal tissue. Patients with low (<50%) HLA-DR expression in the EAC tumor epithelium had significantly worse survival outcomes, compared to those with high expression, in both the tumor core (hazard ratio, HR = 2.178, p = 0.024, n = 70) and leading edge (HR = 2.86, p = 0.013, n = 41). Multivariate analysis demonstrated that low HLA-DR expression in leading edge tumor epithelium was an independent predictor of poor survival, associated with a 2.8-fold increase in disease-associated death (p = 0.023). This study shows that HLA-DR is an independent prognostic marker in EAC tumor epithelium. This may have implications for patient stratification strategies as well as EAC tumor immunology.

MHC class II expression in pancreatic tumors: a link to intratumoral inflammation

Major histocompatibility complex class II antigens (MHC class II) are constitutively expressed by professional antigen presenting cells and present antigenic peptides to specific CD4+ T lymphocytes. MHC class II expression, however, can also be induced on epithelial cells and in a variety of solid tumors. We tested MHC class II expression on tissue samples derived from patients with pancreatic ductal adenocarcinoma (PDAC) and pancreatic endocrine tumors (PET). Immunohistochemistry revealed MHC class II expression in 86 of 112 (76.8%) PDAC samples and in 30 of 43 (70.0%) PET samples. In PDAC and PET, MHC class II expression correlated significantly with severity and activity of intratumoral inflammation, as well as with the infiltration of CD4+ T lymphocytes. High MHC class II expression significantly correlated with a better histological grade of differentiation in PDAC. In vitro MHC class II expression could be induced on PDAC tumor cell lines by interferon-γ. These cells were then able to present the staphylococci enterotoxin B superantigen to T lymphocytes, which resulted in T cell proliferation. Our findings suggest that MHC class II expression on pancreatic tumor cells is induced by the intratumoral inflammatory reaction in pancreatic tumors.

Absent in Melanoma 2 (AIM2) is an important mediator of interferon-dependent and -independent HLA-DRA and HLA-DRB gene expression in colorectal cancers

Absent in Melanoma 2 (AIM2) is a member of the HIN-200 family of hematopoietic, IFN-inducible, nuclear proteins, associated with both, infection defense and tumor pathology. Recently, AIM2 was found to act as a DNA sensor in innate immunity. In addition, we and others have previously demonstrated a high frequency of AIM2-alterations in microsatellite unstable (MSI-H) tumors. To further elucidate AIM2 function in colorectal tumors, we here addressed AIM2-responsive target genes by microarray based gene expression profiling of 22 244 human genes. A total of 111 transcripts were significantly upregulated, whereas 80 transcripts turned out to be significantly downregulated in HCT116 cells, constitutively expressing AIM2, compared with AIM2-negative cells. Among the upregulated genes that were validated by quantitative PCR and western blotting we recognized several interferon-stimulated genes (ISGs: IFIT1, IFIT2, IFIT3, IFI6, IRF7, ISG15, HLA-DRA, HLA-DRB, TLR3 and CIITA), as well as genes involved in intercellular adhesion and matrix remodeling. Expression of ISGs correlated with expression of AIM2 in 10 different IFN-γ treated colorectal cancer cell lines. Moreover, small interfering RNA-mediated knock-down of AIM2 resulted in reduced expression of HLA-DRA, HLA-DRB and CIITA in IFN-γ-treated cells. IFN-γ independent induction of HLA-DR genes and their encoded proteins was also demonstrated upon doxycyclin-regulated transient induction of AIM2. Luciferase reporter assays revealed induction of the HLA-DR promoter upon AIM2 transfection in different cell lines. STAT-signaling was not involved in IFN-γ independent induction of ISGs, arguing against participation of cytokines released in an autostimulating manner. Our data indicate that AIM2 mediates both IFN-γ dependent and independent induction of several ISGs, including genes encoding the major histocompatibility complex (MHC) class II antigens HLA-DR-α and -β. This suggests a novel role of the IFN/AIM2/ISG cascade likewise in cancer cells.

NY-CO-58/KIF2C is overexpressed in a variety of solid tumors and induces frequent T cell responses in patients with colorectal cancer

NY-CO-58/KIF2C has been identified as a tumor antigen by screening antibody responses in patients with colorectal cancer. However, expression had not consequently been examined, and nothing was known about its ability to induce spontaneous T cell responses, which have been suggested to play a role in the development of colorectal cancer. We analyzed 5 colorectal cancer cell lines, and tumor samples and adjacent healthy tissues from 176 patients with epithelial cancers for the expression of NY-CO-58/KIF2C by RT-PCR and Western Blot. T cell responses of 43 colorectal cancer patients and 35 healthy donors were evaluated by ELISpot following stimulation with 30mer peptides or full-length protein. All cell lines and tumor samples from colorectal cancer patients expressed NY-CO-58/KIF2C on the protein and RNA level, and expression levels correlated strongly with Ki-67 expression (r = 0.69; p = 0.0003). Investigating NY-CO-58/KIF2C-specific T cell responses, CD8(+) T cells directed against 1 or more peptides were found in less than 10% of patients, whereas specific CD4(+) T cells were detected in close to 50% of patients. These T cells were of high avidity, recognized the naturally processed antigen and secreted IFN-gamma and TNF-alpha. Depletion of CD4(+)CD25(+) T cells before stimulation significantly increased the intensity of the preexisting response. NY-CO-58/KIF2C is significantly overexpressed in colorectal and other epithelial cancers and expression levels correlate with the proliferative activity of the tumor. Importantly, NY-CO-58/KIF2C was able to induce spontaneous CD4(+) T cell responses of the Th1-type, which were tightly controlled by peripheral T regulatory cells.

CIITA versus IFN-gamma induced MHC class II expression in head and neck cancer cells

A growing body of evidence suggests that optimal induction of systemic anti-tumor immunity requires priming of both the CD4+ and CD8+ T cells that are specific for tumor-associated antigens (TAA). Recently, it was shown that MHC class II positive tumor cells are able to induce tumor-specific CD4+ T cells, and that this event may improve clinical outcome. This has rekindled the interest in modulating MHC class II expression in nonprofessional antigen presenting tumor cells. The class II transactivator (CIITA) is a major regulator of MHC class I and class II expression. We compared, in head and neck cancer cell lines, the effect of stable overexpression of CIITA to treatment with IFN-gamma on the cell surface expression profile of MHC class I and II molecules. Here, we provide evidence that CIITA transfection is more effective than IFN-gamma in inducing MHC class II expression. To more thoroughly explore the mechanisms of MHC class II induction in this context, we used RT-PCR to measure the mRNA expression pattern of HLA-DR, HLA-DM, cathepsin S, and the invariant chain. In contrast to the effect of treatment with IFN-gamma, CIITA transfection did not induce cathepsin S, an important protease responsible for the degradation of the invariant chain, and thus for binding of the peptides to the MHC class II binding groove. These findings may have a significant impact on practical and clinical aspects of tumor immunotherapeutic strategies.

Epithelial human leukocyte antigen-DR expression predicts reduced recurrence rates and prolonged survival in rectal cancer patients

PURPOSE

The development of local and distant recurrences is a major problem in the treatment of rectal cancer patients. In this study, we investigated whether epithelial human leukocyte antigen-DR (HLA-DR) expression allowed discrimination between high and low tumor recurrence rates, and analyzed the mechanism behind its expression.

EXPERIMENTAL DESIGN

The role of IFNgamma in HLA-DR expression was studied in rectal cancer cell lines and tumors by promoter-specific analyses of class II transactivator (CIITA). The predictive value of epithelial HLA-DR expression was investigated by immunohistochemical evaluation of 1,016 rectal tumors, obtained from a large prospective trial. Associations with recurrences and survival were determined by univariate and multivariate log-rank testing.

RESULTS

HLA-DR was induced by IFNgamma in rectal cancer cell lines. Activity of the IFNgamma-inducible pIV-CIITA promoter correlated with epithelial HLA-DR expression in rectal tumors. Patients with HLA-DR-positive tumors developed less frequent local and distant recurrences [1.6% versus 9.1% (P = 0.0015) and 15.3% versus 29.9% (P < 0.0001), respectively, after 5 years of follow-up] and had better survival (78.6% versus 61.3%; P < 0.0001) than patients with HLA-DR-negative tumors. Epithelial HLA-DR was more often found in lower tumor-node-metastasis (TNM) stages. Next to TNM and circumferential resection margin, HLA-DR expression was independently associated with lower distant recurrence rates and prolonged survival.

CONCLUSIONS

Epithelial HLA-DR expression can be used as a marker to discriminate patients with high or low risk of developing recurrences. The possible involvement of IFNgamma, the relationship with lower TNM stages, and the independent effect on recurrence development together suggest that the host immune response plays an important role in controlling tumor cells.

Patterns of constitutive and IFN-gamma inducible expression of HLA class II molecules in human melanoma cell lines

Major histocompatibility complex (MHC) class II proteins (HLA-DR, HLA-DP and HLA-DQ) play a fundamental role in the regulation of the immune response. The level of expression of human leukocyte antigen (HLA) class II antigens is regulated by interferon-gamma (IFN-gamma) and depends on the status of class II trans-activator protein (CIITA), a co-activator of the MHC class II gene promoter. In this study, we measured levels of constitutive and IFN-gamma-induced expression of MHC class II molecules, analysed the expression of CIITA and investigated the association between MHC class II transactivator polymorphism and expression of different MHC class II molecules in a large panel of melanoma cell lines obtained from the European Searchable Tumour Cell Line Database. Many cell lines showed no constitutive expression of HLA-DP, HLA-DQ and HLA-DR and no IFN-gamma-induced increase in HLA class II surface expression. However, in some cases, IFN-gamma treatment led to enhanced surface expression of HLA-DP and HLA-DR. HLA-DQ was less frequently expressed under basal conditions and was less frequently induced by IFN-gamma. In these melanoma cell lines, constitutive surface expression of HLA-DR and HLA-DP was higher than that of HLA-DQ. In addition, high constitutive level of cell surface expression of HLA-DR was correlated with lower inducibility of this expression by IFN-gamma. Finally, substitution A-->G in the 5' flanking region of CIITA promoter type III was associated with higher expression of constitutive HLA-DR (p<0.005). This study yielded a panel of melanoma cell lines with different patterns of constitutive and IFN-gamma-induced expression of HLA class II that can be used in future studies of the mechanisms of regulation of HLA class II expression.

Strong HLA-DR antigen expression on cancer cells relates to better prognosis of colorectal cancer patients: Possible involvement of c-myc suppression by interferon-gamma in situ

Strong HLA-DR antigen expression on cancer cells relates to better prognosis of colorectal cancer patients, although the precise mechanism is controversial. From an immunological point of view, HLA-DR antigen, induced by interferon (IFN)-gamma, is required for tumor-associated antigen recognition by CD4(+) T cells. For instance, as reported previously, the expression of HLA-DR antigen in normal colorectal epithelium immediately adjacent to cancer coincided significantly with the existence of IFN-gamma mRNA in the tissue. From another aspect, IFN-gamma has been revealed to suppress c-myc expression in vivo through a stat1-dependent mechanism, which is important for cell growth, cell cycle and chromosome instability. In the present study, strong HLA-DR-positive expression on cancer cells was significantly related to better prognosis for colorectal cancer patients. High IFN-gamma mRNA expression in situ indicated significantly less activation of c-myc mRNA expression. Further, HLA-DR antigen expression in cancer cells, as well as Dukes stages, was an independent factor for better long-term survival by multivariate analysis. Taken together, IFN-gamma, which induces HLA-DR antigens on the cell surface, also suppresses c-myc expression in situ, and is a possible non-immunological mechanism involved in the better long-term survival of colorectal cancer patients.

Altered Expression of Immune Defense Genes in Pilocytic Astrocytomas

Pilocytic astrocytoma (WHO grade I) is a circumscribed, slowly growing, benign astrocytoma that most frequently develops in the cerebellar hemispheres and in midline structures and occurs predominantly in childhood and adolescence. In contrast to diffusely infiltrating gliomas in adults (e.g. grade II astrocytomas, oligodendrogliomas), survival of patients with pilocytic astrocytoma is excellent after surgical intervention. To search for potential molecular mechanisms underlying its benign biologic behavior, we compared gene expression profiles of pilocytic astrocytomas (8 cases) with those of normal cerebellum (4 cases), low-grade astrocytomas (WHO grade II; 15 cases), and oligodendrogliomas (WHO grade II; 17 cases) by cDNA array analysis. A number of immune system-related genes such as HLA-DRalpha, HLA-DPB1, HLA-DQB1, IgG3, IgGK, FCER1G, A2M, FCRN, IFI-56K, and DAP12 were upregulated in pilocytic astrocytomas relative to normal cerebellum, grade II astrocytomas, and oligodendrogliomas. Genes expressed at higher levels in pilocytic astrocytomas than in grade II astrocytomas and oligodendrogliomas include HLA-DRalpha, HLA-DPA1, HLA-DPB1, HLA-DQB1, A2M, TIMP1, TIMP2, CDKN1A, and SOCS3 and those expressed at lower levels include EGFR and PDGFRA. Hierarchical clustering analysis using the entire set of 1176 genes distinguished pilocytic astrocytomas from grade II astrocytomas and oligodendrogliomas. Clustering analysis using selected subgroups of genes based on their molecular functions revealed that immune system-related genes (75 genes) or cell adhesion, migration, and angiogenesis-related genes (69 genes) showed similar power to the entire gene set for separation of pilocytic astrocytomas from diffusely infiltrating low-grade gliomas. Immunohistochemistry revealed that HLA-DRalpha is expressed diffusely in neoplastic cells in pilocytic astrocytomas, whereas in oligodendrogliomas, expression was limited to scattered reactive astrocytes. These results suggest that gene expression profiles of pilocytic astrocytomas differ significantly from those of diffusely infiltrating low-grade gliomas and that their benign biologic behavior may be related to upregulation of immune defense-associated genes.

Epigenetic inactivation of class II transactivator (CIITA) is associated with the absence of interferon-gamma-induced HLA-DR expression in colorectal and gastric cancer cells

Tightly regulated at the level of transcription, expression of MHC class II molecules varies significantly among gastrointestinal cancers. High levels of MHC class II expression are often associated with a better prognosis, which is indicative of the involvement of CD4+ lymphocytes in tumor suppression, but the molecular mechanism by which MHC class II expression is regulated remains unclear. In the present study, we investigated the expression of one inducible MHC class II molecule, HLA-DR, and its coactivators in a panel of colorectal and gastric cancer cell lines. Interferon-gamma induced expression of HLA-DR in 14 of 20 cell lines tested; the remaining six cell lines did not express HLA-DR. Analysis of the expression of transcription factors and coactivators associated with HLA-DR revealed that the loss of CIITA expression was closely associated with the absence of HLA-DR induction. Moreover, DNA methylation of the 5' CpG island of CIITA-PIV was detected in all cancer cells that lacked CIITA. The methylation and resultant silencing of CIITA-PIV depended on the activities of two DNA methyltransferases, DNMT1 and DNMT3B, and their genetic inactivation restored CIITA-PIV expression. It thus appears that CIITA methylation is a key mechanism that enables some gastrointestinal cancer cells to escape immune surveillance.

Identification of an HLA-A0201-restricted CTL epitope generated by a tumor-specific frameshift mutation in a coding microsatellite of the OGT gene

Deficient DNA mismatch repair results in microsatellite instability and might induce shifts of translational reading frames of genes encompassing coding microsatellites. These may be translated in truncated proteins, including neo-peptide tails functioning as tumor rejection antigens, when presented in the context of MHC class I. Recently, others and we identified a frameshift mutation in the coding T(10) microsatellite of the O-linked N-acetylglucosamine transferase gene (OGT) occuring in up to 41% of microsatellite unstable colorectal cancers. Here we describe a novel HLA-A0201-restricted cytotoxic T lymphocyte (CTL)-epitope (28-SLYKFSPFPL; FSP06) derived from this mutant OGT-protein. FSP06-specific CTL-clones killed peptide-sensitized target cells and tumor cell lines expressing both HLA-A0201 and mutant OGT proteins. This demonstrates that FSP06 is endogenously expressed and represents a CD8(+)-T cell epitope. Our data corroborate the concept of frameshift peptides constituting a novel subset of tumor-associated antigens specifically encountered in cancer cells with deficient mismatch repair.

Major histocompatibility complex status in breast carcinogenesis and relationship to apoptosis

Major histocompatibility complex (MHC) molecules are of central importance in regulating the immune response against tumors. In this study we used immunohistochemistry to study human leukocyte antigen (HLA) class I and II antigen expression in normal breast tissues and benign, preneoplastic, primary, and metastatic breast lesions using antibodies against beta-2-microglobulin (beta2-m), heavy-chain, and HLA-DR antigens. Whereas all normal tissues and benign lesions were positive for beta2-m and HLA-A, -B, and -C antigens, total loss of HLA class I antigens was found in 37% (11 of 30) of in situ carcinomas, in 43% (56 of 131) of the primary tumors, and in 70% (31 of 45) of the lymph node metastases. HLA-DR was also underexpressed in breast cancer cells; thus 20% (6 of 30) of in situ carcinomas, 15% of invasive carcinomas (20 of 131), and only 1 metastatic case were positive for this antigen. Both HLA class I and II antigen expression were more frequently down-regulated in metastatic lesions than in primary breast lesions (P <0.05), and a tendency toward a simultaneous defective expression of HLA class I and II antigens was observed in primary carcinomas (P = 0.07). However, no correlation was found between the expression of any of the aforementioned molecules and pathological parameters or survival. Interestingly, HLA class I expression was expressed more frequently in tissues with high apoptotic activity and was significantly associated with the expression of the proapoptotic bax gene (P = 0.02), and was inversely associated with expression of the antiapoptotic bcl-2 gene (P = 0.03). We conclude that alterations in HLA class I and II antigen expression are early events in breast carcinogenesis and play significant roles in metastatic progression. In addition, their expression is correlated with apoptosis-regulating proteins, which may influence the cytotoxicity of T cells against HLA class I-specific tumor antigens.

Targeted therapy of solid malignancies via HLA class II antigens: a new biotherapeutic approach?

Intracellular signals, delivered in professional antigen-presenting cells following the engagement of major histocompatibility complex (MHC) class II molecules, activate a variety of cellular functions that also contribute to efficient antigen presentation. As far as human malignancies, the signaling ability of human leukocyte antigens (HLA) class II molecules is a rather well-characterized event in hematologic tumors; in contrast, very limited evidences are available in solid neoplasias of different histotypes that may constitutively express HLA class II antigens. Among solid malignancies, a significant proportion of human cutaneous melanomas have been shown to express HLA class II molecules, and cutaneous melanoma undoubtedly represents a 'model disease' to investigate tumor immunobiology, to unveil the molecular basis underlying the interactions between neoplastic cells and host's immune system, and ultimately to set up new bio-immunotherapeutic approaches. Upcoming preclinical evidences unveil a signaling potential of HLA-DR antigens expressed on melanoma cells, and suggest for the clinical implication of HLA class II molecules as novel therapeutic targets. Therefore, in this review, we will focus on the emerging role of HLA class II antigens as intracellular signal transducing elements in neoplastic cells of the melanocytic lineage, emphasizing their foreseeable role in targeted therapy of human melanoma and potentially of HLA class II antigens-positive tumors of different histology.

Prognostic value of the CD4+/CD8+ ratio of tumour infiltrating lymphocytes in colorectal cancer and HLA-DR expression on tumour cells

The purpose of this study was to clarify whether HLA-DR expression of colorectal tumour cells or the CD4+/CD8+ ratio of the tumour infiltrating lymphocytes is significantly associated with the prognosis of colorectal cancer. Using flow cytometry, we studied the tumour cell expression of the HLA class II in 70 enzymatically dissociated colorectal cancers and the phenotype of tumour infiltrating lymphocytes (TILs) in 41 cases. There was no trend in 5-year survival between three levels (low, medium, high) of HLA-DR expression on the tumour cells. Patients with low CD4+/CD8+ ratios had a better clinical course, with significantly higher 5-year survival, p=0.046, independent of the Dukes stage and age. Our results have implications for tumour immunology; colorectal cancer cells might be a target for cytotoxic T-lymphocytes, however the tumour cells are not able to initiate an immune response. Stimulation of the immune system could possible be obtained using dendritic cells cultured in vitro and loaded with tumour antigens.

Immunology and immunotherapy of colorectal cancer

This review critically discusses data on immunology of colorectal cancer, starting from pathology and molecular biology, and then considering the molecular characterisation of colon cancer antigens and the clinical trials of immunotherapy. A careful evaluation of histopathological studies on intra-epithelial infiltration by T cells in primary tumours, together with the analysis of HLA expression by colorectal cancer cells, suggest that anti-tumour T cell immune responses may take place in vivo in those patients, influencing prognosis and shaping the tumour immunological profile. Moreover, the molecular characterisation of tumour antigens expressed by colorectal carcinomas, together with improved understanding of mechanisms of the immune response and more sensitive methods for the in vivo detection of T cell responses, are now allowing researchers to design new and more effective vaccination protocols, with encouraging preliminary results. By drawing together the experimental evidence from different research fields, this review provides support for the concept that colorectal carcinoma is immunogenic and may reasonably be considered as a target for immunotherapy, and attempts to address critical issues and envisage future developments in this challenging research field.

Genetic and protein markers related to in situ growth and multiplicity in small sporadic colorectal adenomas

BACKGROUND

Some early genetic events in the development of colorectal adenomas are known, but their relationship to in vivo growth characteristics is uncertain. This study compared in situ size changes and other clinicopathological variables with selected genetic and protein markers.

METHODS

56 adenomas (< or = 10 mm) from 39 patients were analysed for APC, CTNNB1 and K-ras mutations, allelic imbalance on 1p and 18q, microsatellite instability and immunohistochemical expression of HLA-DR, BAX, BCL-2 and Ki-67. For 42 of the adenomas, in situ growth was measured over 3 years. The total number of polyps in each patient was recorded.

RESULTS

K-ras was mutated in 8/56 adenomas. None of the regressing adenomas revealed such mutations, compared to 20% in those that maintained or increased their size. Multivariate linear regression analysis showed that tumour growth was higher in females compared to males, and was even higher in the presence of a K-ras mutation. APC mutations were found in 37/56 adenomas. CTNNB1 mutations were found in 2/19 adenomas without APC mutation. Deletions of 1p were found in 12/56 adenomas and, seemingly, most frequent in patients with few tumours. The most frequently expressed protein was BAX (33/41), but neither this nor the other proteins showed associations with an in situ growth pattern.

CONCLUSION

The multivariate linear regression model showed that patient gender and the presence of K-ras mutation had significant effects on tumour growth. The lack of the proliferative stimulus resulting from a K-ras mutation may contribute to the process of adenoma regression.

Association of ovarian tumor epithelium coexpressing HLA-DR and CA-125 antigens with tumor infiltrating cytotoxic T lymphocytes

Understanding of the relationship between tumor infiltrating cytotoxic T lymphocytes (CD 8(+)TILs) and tumor cells as well as tumor-associated antigens is important and may reflect the extent of immune response of the patient to the tumor, thus providing a useful clue relevant to the prognosis. The purpose of this study was to determine the relationship between the expression of HLA-DR and CA-125 antigens and the presence of CD 8(+)TILs with regard to the established clinicopathological factors of ovarian carcinomas using immunohistochemical methods. Thirty-one ovarian carcinomas consisting of 20 serous, 7 mucinous, and 4 clear cell types were examined. Of these, 18 (58%) and 22 (71%) were positive for HLA-DR and CA-125 antigens respectively, and the overall mean number of the CD 8(+)TILs was 7.2+/-2.9. A significant association was observed between the mean number of CD8(+)TILs and tumor grade (P=0.01), disease stage (P=0.003), and patient outcome (P=0.01). The mean number of CD 8(+)TILs in HLA-DR positive (8.6+/-2.2) or CA-125 positive (8.4+/-2.1) tumors was significantly higher than that in HLA-DR negative (5.2+/-2.5; P=0.0003) or CA-125 negative (4.2+/-2.2; P=0.00002) tumors. These significant levels were further enhanced by one order of magnitude when the mean number of CD 8(+)TILs in tumors positive for both HLA-DR and CA-125 antigens (9.1+/-1.7) was compared to that in HLA-DR negative or CA-125 negative tumors. The frequency of cancer-related deaths in HLA-DR and CA-125 positive tumors was significantly lower than in the negative tumors (P=0.01). These data suggest that concurrent expression of HLA-DR and CA-125 antigens may augment the immune response of the patient to the tumor, thus providing a potential clue relevant to the prognosis.

Strong HLA-DR expression in microsatellite stable carcinomas of the large bowel is associated with good prognosis

Progression of colorectal cancer may follow either of two main genetic routes: the chromosome- or microsatellite-instability pathways. Association between the patients' prognosis and microsatellite instability has been questioned. Improved survival has previously been found in patients with expression of HLA-DR antigens on their tumour cells. In this study, the expression of HLA-DR antigen was investigated by immunohistochemistry in 357 large bowel carcinomas stratified by microsatellite instability status. Sixteen per cent of the tumours showed strong HLA-DR expression and 35% had weak DR expression. We confirmed that patients with strong positive HLA-DR staining had improved survival (P<0.001) compared to patients with no HLA-DR expression. Strong epithelial HLA-DR staining was significantly associated with high level of microsatellite instability (P<0.001). In the subgroup of tumours with characteristics typical of the chromosomal instability phenotype, i.e. in microsatellite-stable tumours, the patients positive for the HLA-DR determinants showed better survival than those without HLA-DR expression. The protective effect of HLA-DR expression on survival was confirmed by multivariate analysis, both in the whole patient group and in the microsatellite-stable/microsatellite instability-low group. This might be explained by enhanced T-cell mediated anti-tumour immune responses against tumour cells in the HLA-DR positive tumours. The finding of better patient survival in the subgroup of strong HLA-DR positive microsatellite-stable tumours may have clinical implications for these patients.

Frameshift-mutation-derived peptides as tumor-specific antigens in inherited and spontaneous colorectal cancer

The functional role and specificity of tumor infiltrating lymphocytes (TIL) is generally not well characterized. Prominent lymphocyte infiltration is the hallmark of the most common form of hereditary colon cancer, hereditary nonpolyposis colon cancer (HNPCC) and the corresponding spontaneous colon cancers with the microsatellite instability (MSI) phenotype. These cancers are caused by inherited or acquired defects in the DNA mismatch-repair machinery. The molecular mechanism behind the MSI phenotype provides a clue to understanding the lymphocyte reaction by allowing reliable prediction of potential T cell epitopes created by frameshift mutations in candidate genes carrying nucleotide repeat sequences, such as TGF beta RII and BAX. These tumors therefore represent an interesting human system for studying TIL and characterizing tumor-specific T cells. We here describe T cell reactivity against several T helper cell epitopes, representing a common frameshift mutation in TGF beta RII, in TIL and peripheral blood lymphocytes from patients with MSI(+) tumors. The peptide SLVRLSSCVPVALMSAMTTSSSQ was recognized by T cells from two of three patients with spontaneous MSI(+) colon cancers and from all three patients with HNPCC. Because such mutations are present in 90% of cancers within this patient group, these newly characterized epitopes provide attractive targets for cancer vaccines, including a prophylactic vaccine for individuals carrying a genetic disposition for developing HNPCC.

A model for potential tumor immunotherapy based on knowledge of immune mechanisms responsible for spontaneous abortion

Attempts to treat various cancers by immunotherapy have been tried for about 50 years. Most studies have focused on improving cytotoxic T lymphocyte (CTL) responses against various tumors. Immunotherapy has been both active and passive, and results have been modest at best. Spontaneous abortion (SAB) of pregnancies could in some ways resemble remission of a tumor. Both tumors and conceptusses are faced with a similar problem -- how to grow in a host in a vascular rich area, and yet escape immune surveillance despite both entities being an allogenic stimulus. In general, the fetus is far more immunogenic than a spontaneous tumor, and yet abortuses seem to avoid CTL responses but are sometimes invaded by natural killer (NK) cells. There are data suggesting that SAB will occur if there is inhibition of production of an immunosuppressive protein called progesterone-induced blocking factor (PIBF). This protein inhibits NK cell cytolysis and influences TH2 cytokine dominance over TH1. If some tumors avoid NK cell destruction through a PIBF mechanism, perhaps an active rejection of these tumors could be achieved by inhibiting PIBF production by treating with a progesterone receptor antagonist. Passive immunization could also be considered by conjugative radionuclide or toxic chemical to a PIBF antibody which may be tumor specific since PIBF is not produced in normal tissue. The first step should be to see if PIBF can be detected in the peripheral circulation in patients with certain tumors.

Loss of MHC class II expression is associated with a decrease of tumor-infiltrating T cells and an increase of metastatic potential of colorectal cancer: immunohistological and histopathological analyses as compared with normal colonic mucosa and adenomas

We immunohistologically investigated 76 cases of primary colorectal cancer and 13 cases of adenoma to clarify the relationship of MHC class II expression with the grade of differentiation, the density of tumor-infiltrating lymphocytes, and the incidence of metastasis to lymph nodes. MHC class II expression was mostly negative in normal colonic epithelium. In contrast, 32 out of 76 cases (42%) of cancer and five out of 13 cases (38%) of adenoma were positive for MHC class II. MHC class II expression was higher in well-differentiated than in poorly differentiated adenocarcinoma. The density of infiltrating lymphocytes was higher in cancer than in the normal mucosa, and higher in MHC class II-positive tissues than in negative lesions. The incidences of lymphatic invasion and cancer metastasis to lymph nodes were definitely higher in MHC class II-negative cancers than in MHC class II-positive cancers. MHC class II was rarely expressed in metastatic cancer cells of lymph nodes. These results indicated that the loss of MHC class II is correlated with the incidence of metastasis to regional lymph nodes.

Independent prognostic value of eosinophil and mast cell infiltration in colorectal cancer tissue

Overall peritumoural inflammatory cell infiltration is a prognostic variable in solid tumours, but the survival-related impact of the individual cell types within the infiltrate has still not been fully evaluated and compared with the conventional disease classification. In the present study, the prognostic value of individual white cell counts in the peritumoural inflammatory infiltrate in colorectal cancer was assessed. Intra-operative tumour tissue samples from 584 patients undergoing elective surgery for colorectal cancer were included. None of the patients received pre- or post-operative adjuvant chemotherapy. Tissue blocks were cut from the periphery of the tumours and embedded in paraffin. All blocks included both tumour tissue and normal bowel tissue. Serial sections of 4 microm were analysed for tumour tissue inflammatory cell infiltration using a computer- and video-assisted microscope, which allowed semi-automated quantification of cells within a fixed area. Total white cells and individual counts of eosinophils, neutrophils, mast cells, lymphocytes, and plasma cells were evaluated in every tumour specimen. Stratification into four groups with similar numbers of events was used to dichotomize the cell counts with respect to survival. The median observation period was 61 (49-75) months. In a multivariate analysis including Dukes' stage, gender, age, peri-operative blood transfusion, tumour location, and counts of specific inflammatory cells, only advanced Dukes' stage ( p< 0.0001), high age ( p=0.0003), and tumour location in the rectum predicted poor survival, while high counts of eosinophils ( p=0.006) and mast cells ( p=0.02) predicted good survival. Tumour-associated eosinophilia and mastocytosis appear to be independent prognostic variables in colorectal cancer. Future studies should investigate the potential biological role of tumour tissue eosinophils and mast cells in the modulation of tumour growth.

Characterisation of tumour infiltrating lymphocytes and correlations with immunological surface molecules in colorectal cancer

Using flow cytometry, we studied the phenotype of tumour infiltrating lymphocytes (TILs) in 41 enzymatically dissociated colorectal cancers and compared this to the expression of HLA class I and II and CD80 on tumour cells. We studied the possible enzymatic damage to various surface markers after enzymatic dissociation. The reproducibility of flow cytometric determinations obtained from TILs was good (kappa value: 0.79). The median CD4+/CD8+ ratio was 2.2. Approximately 43-45% (median of cells in each tumour) of both the CD4(+)- and the CD8(+)-TILs expressed HLA class II; 14.2% of the CD4(+)-TILs expressed CD25 and none of the CD8(+)-TILs expressed CD25. CD3-/CD16+/CD56(+)-TILs were very infrequent. Expression of HLA class II did not correlate with any lymphocyte surface markers. Since TILs are "turned off" rather than stimulated when tumour cells express HLA class II but not CD80, the lack of correlations could be due to anergy.

HLA-DR expression is a significant prognostic factor in laryngeal cancer. A morphometric study

HLA-DR antigen expression in tumour cells was investigated in 68 laryngeal carcinomas. The tissue sections were studied by a morphometric method using a computer image analysis system. Although the highest number of HLA-DR-positive cells was observed in the groups with the lowest clinical stage, these differences did not reach statistical significance. Analysis of survival showed a significantly different survival time of patients classified as HLA-DR positive (10% and more HLA-DR+tumour cells) compared to those classified as HLA-DR negative. There were no significant differences in survival times between patients with glottic and extraglottic cancers, or between patients with various grades of histological malignancy.

Flow cytometric investigation of immune-response-related surface molecules on human colorectal cancers

Our purpose was to clarify whether human colorectal cancer cells are equipped to present tumour-associated-antigens to the immune system, and whether this ability correlates with lymphoid infiltration, the Dukes' stage and Jass classification. Enzymatically dissociated tumour cells from 70 different colorectal cancers were monitored by multiparameter flow cytometry. Gating on EP4+ cells, the expression of the surface molecules HLA class I, HLA class II, CD80 (B7-1), CD54 (ICAM-I) and CD58 (LFA-3) was evaluated. In 60 of 70 tumours, all tumour cells expressed HLA class I, in 10 tumours 15-96% of the tumour cells expressed HLA class I. In 1 tumour, all tumour cells expressed HLA class II, in 67 tumours some expressed HLA class II, in 2 tumours none expressed HLA class II. Expression of CD58 was heterogeneous, and there was no or only sparse expression of CD80 and CD54. Expression of the HLA class I molecules, but not the class II, was correlated with lymphoid infiltration and the Jass classification. Expression of these surface molecules was not correlated with the Dukes' stage. The tumour cells were generally equipped to present antigens to the effector arm of the immune system since HLA class I is expressed, but the tumour cells were not optimal in stimulating an immune response, since HLA class II and CD58 were only marginally expressed and CD80 and CD54 were absent.

A comparison of flow cytometry and immunohistochemistry in human colorectal cancers

In human colorectal cancer it has been reported that some tumours lack the HLA-ABC antigens. This has been interpreted as reflecting tumour escape from the immune system. Earlier data have been obtained by immunohistochemistry. In this study, we compared the expression of HLA-ABC, HLA-DR, CD80 (B7-1) and CD54 (ICAM-1) in 20 tumours using both a conventional immunohistochemistry two-layer technique and multiparameter flow cytometry, gating on an epithelial cell marker. Colorectal cancer tissue used in flow cytometry was dissociated with collagenase, deoxyribonuclease and hyaluronidase. The intensity of expression of HLA-ABC, HLA-DR and CD80 was unaffected by the enzymes, but CD54 was decreased by 30%. The reproducibility of flow cytometry was good. Microscopy of sections revealed that about 5% of each tumour sample consisted of normal epithelium, but even after correction for this, flow cytometry was superior to immunohistochemistry in 33 out of 80 cases, and showed that tumours described as HLA-ABC negative by immunohistochemistry were in fact weakly positive for HLA-ABC. We conclude that flow cytometry and immunohistochemistry are complementary, and that flow cytometry is superior to immunohistochemistry for detecting antigens/epitopes present in low amounts.

Induction of a T- and B-cell response against a unique amino acid sequence of the mouse IgG2A hinge region in a MAb-treated patient

A patient with malignant glioblastoma was treated with intratumoral infusions of the murine MAb425 (IgG2A) directed against the epidermal growth factor receptor. At the 10th infusion, the patient developed somnolence, fever and headache. The symptoms increased during the subsequent 48 hr but then gradually disappeared within a week. The cerebrospinal fluid (CSF) contained increased concentrations of interleukin-2. The main CSF cell subset was CD4 T-cells. A marked blood lymphocyte proliferative response against mouse IgG2A was noted. The reactive T-cell epitope(s) could be localized to a 14 amino acid (RGPTIKPCPPCKCP) long peptide of the hinge region. A B-cell response (IgG antibodies) against this peptide was also induced.

K-ras mutations and prognosis in large-bowel carcinomas

BACKGROUND

Colorectal carcinogenesis is regarded as a multistep process involving several genetic alterations, with mutation in the K-ras gene in about half of the tumours. We aimed at clarifying the role of this genetic alteration related to survival and clinicopathologic variables.

METHODS

One hundred large-bowel carcinomas operated on between 1978 and 1982 were studied for the presence of point mutations in codons 12 and 13 of the K-ras gene, using enriched polymerase chain reaction amplification, restriction fragment length polymorphism analysis, and direct sequencing.

RESULTS

Forty mutations were found (40%): 31 in codon 12 and 9 in codon 13, 7 different types. There was no relationship between tumours with and without K-ras mutations with regard to Dukes' stages, age or sex of the patient, tumour localization, histologic grade, DNA ploidy pattern, HLA-DR staining pattern, or survival. Samples from 5 different localizations in 7 carcinomas showed identical K-ras mutation pattern, as did 19 recurrences/ metastases originating from 11 carcinomas.

CONCLUSIONS

When present, the primary tumour shows homogeneous distribution of K-ras mutation, and the mutation follows the carcinoma in the secondary deposit, regardless of lymphogenous or hematogenous spread. The presence of K-ras mutation does not seem to have prognostic significance for the patient, and the precise nucleotide change is furthermore not predictive of tumour behaviour.

Augmentation of immune response by an analog of the antigenic peptide in a human T-cell clone recognizing mutated Ras-derived peptides

T-cells that recognize mutated p21 Ras are relevant to immune surveillance systems against cancer. We report here evidence that immune responses of a T-cell clone recognizing mutated p21 Ras can be augmented by an analog peptide. Using spleen cells from a gastric cancer patient, we established the CD4+ alpha beta Th1-like clone C27 that recognizes wild-type (3EYKLVVVGAGGVGKS17) and mutated p21 Ras protein molecules and peptides, in an HLA-DR1-restricted manner. C27 responded prominently to mutated Ras peptides carrying Val or Ala at position 12, as compared to wild-type and other mutated peptides. C27 also exhibited a much stronger response to a mutated p21 Ras whole-protein molecule-carrying Val at position 12, as compared with the wild-type protein. The proliferative response and production of GM-CSF, TNF-alpha, and IFN-gamma by C27 were further augmented by replacing the possible first DR anchor 4Tyr of the mutated Ras peptide with Trp, a more potent anchor residue for the DR1 molecule. Enhancement of peptide antigenicity by substituting the HLA anchor residue of an antigenic peptide recognized by tumor-reactive T-cells may prove to be a novel strategy for antigen-specific cancer immunotherapy.

Infiltration of mononuclear inflammatory cells into primary colorectal carcinomas: an immunohistological analysis

Local immunoregulation mediated by mononuclear tumour-infiltrating cells is considered of importance for tumour progression of colorectal cancer, although the balance between immunosuppressor and cytotoxic activities is unclear. Colorectal cancers from 26 patients were investigated using a panel of monoclonal antibodies in order to identify subsets of mononuclear inflammatory cells and to study their pattern of distribution in relation to tumour stage and cytotoxic immune reactivity against the tumour. In all but five tumours, mononuclear cells, lymphocytes or monocytes were present in fairly large numbers, particularly in the stroma. The infiltration of CD4+ mononuclear cells predominated over the CD8+ subset. Infiltration near the tumour cells was found in four cancers only. Stromal infiltration of CD11c+ macrophages was found in all but eight tumours. Small regressive areas, in which the histological architecture of the tumours was broken down, were found in 17 tumours with intense or moderate infiltration by CD4+ lymphocytes or CD11c+ macrophages. Probably this destruction of tumour tissue was caused by cytotoxic activity of the tumour-infiltrating mononuclear cells. In Dukes' class A and B tumours, CD4+ lymphocytes predominated over CD4+ cells with macrophage morphology, but the latter were increasingly found in Dukes' class C and D disease. The occurrence of MHC II-positive macrophages and lymphocytes in different Dukes' classes was similar to that of CD4+ cells. In contrast to this, CD11c+ and CD11a+ cells were more frequent in Dukes' A and B class tumours compared with Dukes' C and D. Four out of nine tumours of the latter stages showed a poor inflammatory reaction. The interpretation of our results is that the subsets of tumour-infiltrating mononuclear cells change with advancing Dukes' class and that the local immune control is gradually broken down in progressive tumour growth, even if some cytotoxic activity is still present.

K-ras mutations and HLA-DR expression in large bowel adenomas

A total of 72 sporadic colorectal adenomas in 56 patients were studied for the presence of point mutations in codons 12 and 13 of the K-ras gene and for HLA-DR antigen expression related to clinicopathological variables. Forty K-ras mutations in 39 adenomas were found (54%): 31 (77%) in codon 12 and nine (23%) in codon 13. There was a strong relationship between the incidence of K-ras mutations and adenoma type, degree of dysplasia and sex. The highest frequency of K-ras mutations was seen in large adenomas of the villous type with high-grade dysplasia. Fourteen out of 15 adenomas obtained from 14 women above 65 years of age carried mutations. HLA-DR positivity was found in 38% of the adenomas, large tumours and those with high-grade dysplasia having the strongest staining. Coexpression of K-ras mutations and HLA-DR was found significantly more frequently in large and highly dysplastic adenomas, although two-way analysis of variance showing size and grade of dysplasia to be the most important variable. None of the adenomas with low-grade dysplasia showed both K-ras mutation and HLA-DR positivity (P = 0.004). K-ras mutation is recognised as an early event in colorectal carcinogenesis. The mutation might give rise to peptides that may be presented on the tumour cell surface by class II molecules, and thereby induce immune responses against neoplastic cells.

Histamine-2 receptor antagonists as immunomodulators: new therapeutic views?

Considerable evidence has emerged to suggest that histamine participates in the regulation of the inflammatory response, immune reaction, coagulation cascade, and cardiovascular function. Furthermore, histamine may play a major role in the growth of normal and malignant tissue as a regulator of proliferation and angiogenesis. Specific histamine receptors have been identified on the surface of bone marrow cells, immune competent cells, endothelial cells, fibroblasts, and also on malignant cells. This has prompted research in regulation by specific histamine receptor agonists and antagonists. Results from such studies are currently accumulating and suggest that the histamine-2 receptor antagonists have potential beneficial effects in the treatment of certain malignant, autoimmune and skin diseases, either alone or in combination with other drugs. The beneficial effect of histamine-2 receptor antagonists as adjuvant single drugs to reduce trauma-, blood transfusion- and sepsis-induced immunosuppression has led to research in combined treatment regimens in major surgery, particularly, of patients operated on for malignant diseases.

HLA-DR antigen expression in colorectal carcinomas: influence of expression by IFN-gamma in situ and its association with tumour progression

The authors attempted to investigate the host's immune response against colorectal carcinoma through the expression of HLA-DR antigen on carcinoma cells (Ca) on normal epithelia immediately adjacent to carcinoma (AN) in relation to tumour progression. The expression of HLA-DR antigen on Ca and on normal epithelia, both on AN and those 5-10 cm removed from the carcinoma (RN), were examined immunohistochemically. mRNAs of cytokines, IFN-gamma and TNF-alpha, were detected by reverse transcription-polymerase chain reaction (RT-PCR) in both carcinoma and remote normal tissues. The expression of HLA-DR antigen on AN was significantly increased compared with RN. Patients with tumours showing HLA-DR staining both in Ca and AN were in less advanced Dukes' stages (Dukes' A or B) compared with those without the stain. Furthermore, the expression of HLA-DR antigen in normal mucosa coincided significantly with the existence of IFN-gamma mRNA. Detection in carcinoma tissues of IFN-gamma mRNA that leads to the induction of HLA-DR antigen on AN could be an indicator of a host's immune response to carcinoma. These in vivo observations might be clinically applicable to the prediction of patients' immune responsiveness to carcinomas.

Lymphocyte subset infiltration patterns and HLA antigen status in colorectal carcinomas and adenomas

Fifty eight large bowel adenocarcinomas and 20 adenomas were studied immunohistochemically, using fresh frozen tissue sections, with regard to lymphocyte subpopulations (CD3, CD4, CD8, CD19, and CD20) in the inflammatory infiltrate and to expression of human leucocyte antigens (HLA-ABC, HLA-A2, and HLA-DR). The findings were related to differentiation and Duke's stage of carcinoma. The inflammatory infiltrate was found to have a phenotype that remained constant irrespective of the intensity of the inflammation. CD4 and CD3 positive cells predominated with fewer CD8 positive cells and a scanty diffuse CD19/20 positive cell population. CD19/20 follicular aggregates were common at the advancing margin of the carcinomas. There was no significant association with Duke's stage, differentiation or HLA status. HLA changes (ABC loss, A2 loss, and DR gain) were associated with differentiation, being more common and more extensive in poorly differentiated carcinomas. HLA-A2 loss was also associated with stage of progression of carcinoma. Inflammation associated with adenomas was found to have a similar phenotype to that associated with carcinomas. HLA changes in adenomas were uncommon, being seen in only one of our 20 cases.

Different patterns of HLA-DR antigen expression in normal epithelium, hyperplastic and neoplastic malignant lesions of the breast

Fifteen samples of non-tumoural breast tissue, 24 cases of benign lesions, four biopsies of inflammatory carcinomas and 94 tumour samples of primitive mammary carcinomas were analysed for HLA class II expression. We found, first, that HLA class II antigens were detectable in all cases of non-neoplastic breast tissue. Secondly, HLA class II antigen expression was notably increased in benign neoplasms and hyperplastic lesions. In contrast, only 32 out of 94 carcinomas showed expression of HLA-DR antigens, 17 tumours had HLA-DP antigens and 11 carcinomas were positive for the presence of DQ molecules. The expression of class II antigen was associated with the degree of histological differentiation (P < 0.05) but was independent of stromal leucocytic infiltration. Thirdly, HLA-DR was very strongly expressed in intravascular tumoural thrombi, especially in the 'inflammatory carcinomas'. The immunophenotype of inflammatory infiltrate was analysed in benign and malignant lesions. In malignant lesions the mean number of inflammatory cells was significantly higher than in benign lesions. Interestingly, we found no differences in the amount and composition of inflammatory infiltrate between HLA-DR positive and negative tumours.

Heat shock protein 70 and HLA-DR molecules tissue expression. Prognostic implications in colorectal cancer

PURPOSE

The expression of 70,000-Da heat shock protein (HSP 70) and HLA-DR molecules on cancer cells influences immunologic mechanisms that may be of some prognostic significance. The purpose of this study was to examine the relationship among immunohistochemical HSP 70, HLA-DR expression, and clinicopathologic tumor variables, as well as patient survival in a series of 128 colorectal carcinomas.

METHOD

A three-step immunoperoxidase staining technique was undertaken for detection of both markers.

RESULTS

Of the examined carcinomas 77.3 percent were HSP 70-positive and 74.2 percent were HLA-DR-positive. Increased HSP 70-positive expression correlated significantly with low differentiation (P < 0.05), showed a tendency to characterize advanced stages of disease, and was clearly associated with worse overall survival (P < 0.05). The highest rate of HLA-DR positivity was demonstrated in early stages and was significantly associated with more favorable prognosis (P < 0.001). HSP 70-positive/HLA-DR-negative patients had worse overall survival compared with the rest (P < 0.001).

CONCLUSIONS

The resulting opposite effects on prognosis of examined markers seem to be related to different pathophysiologic functional roles on tumor immunology.