The expression of HLA class I antigens in germ cell testicular cancer

Overexpression of SerpinB9 in non-seminomatous germ cell tumors

Serpinb9 is an inhibitor of granzyme B and is potentially involved in the immune escape of tumor cells. In the present study, bioinformatics analysis using open databases suggested that SerpinB9 is overexpressed in testicular embryonal carcinoma. Immunohistological analysis was performed on 28 cases of testicular germ cell tumors to investigate the relationship between SerpinB9 expression in testicular germ cell tumors and the tumor immune environment. SerpinB9 was significantly upregulated in the non-seminoma group and inversely correlated with the number of tumor-infiltrating CD8-positive cells. In addition, yolk sac tumors were characterized by the loss of human leukocyte antigen-class I expression. These findings suggest that SerpinB9 contributes to the immune escape of testicular germ cell tumors. Targeting therapy for SerpinB9 might therefore be useful in immunotherapy for testicular germ cell tumors resistant to immune checkpoint inhibitors.

Mechanisms of tumor evasion

The results from in vitro immunological experiments, murine tumor models and patients with cancer clearly demonstrate that tumors have multiple mechanisms to evade the immune response. During the early stages of tumor development malignant cells can be poor stimulators, present poor targets or become resistant to the innate immune response, while at later stages, progressively growing tumors impair the adaptive immune response by blocking the maturation and function of antigen presenting cells and causing alterations in T cell signal transduction and function. Preliminary results also suggest a correlation between some of these changes and an increased metastatic potential of the tumor cells, a diminished response to immunotherapy, and poor prognosis. Carefully coordinated basic research studies and clinical immunotherapy trials will be required to fully determine the impact on the outcome of the disease and the response to treatment. However, understanding the mechanisms used by tumor cells to evade the immune system could result in new therapeutic approaches for preventing and/or reversing these immune alterations and have the potential of improving the current results of immunotherapy trials.

Classical and nonclassical HLA class I antigen and NK Cell-activating ligand changes in malignant cells: current challenges and future directions

Changes in classical and nonclassical HLA class I antigen and NK cell-activating ligand expression have been identified in malignant lesions. These changes, which are described in this chapter, are believed to play a major role in the clinical course of the disease since both HLA class I antigens and NK cell-activating ligands are critical to the interaction between tumor cells and components of both innate and adaptive immune systems. Nevertheless, there is still debate in the literature about the biologic and functional significance of HLA class I antigen and NK cell-activating ligand abnormalities in malignant lesions. The reasons for this debate are reviewed. They include (i) the incomplete association between classical HLA class I antigen changes and the clinical course of the disease; (ii) the relatively limited number of malignant lesions that have been analyzed for nonclassical HLA class I antigen and NK cell-activating ligand expression; and (iii) the conflicting data regarding the role of immunoselection in the generation of malignant cells with HLA antigen and NK cell-activating ligand abnormalities. The technical limitations associated with the assessment of HLA antigen and NK cell-activating ligand expression in malignant lesions as well as the immunological and nonimmunological variables that may confound the impact of HLA antigen and NK cell-activating ligand changes on the clinical course of the disease are also discussed. Future studies aimed at overcoming these limitations and characterizing these variables are expected to provide a solution to the current debate regarding the significance of HLA class I antigen and NK cell-activating ligand abnormalities in malignant lesions.

Activated status of tumour-infiltrating lymphocytes and apoptosis in testicular seminoma

Testicular seminoma is characterized by a prominent lymphoid infiltrate and an excellent prognosis. Cytotoxic T-lymphocytes (CTLs) infiltrating seminoma tumour nests constitute a major subset of the lymphoid infiltrate. The objective of this study was to determine whether CTLs express markers of cytotoxic potential and activity and whether the number of activated CTLs correlates with the extent of apoptosis in testicular seminomas, as opposed to non-seminomatous testicular germ cell tumours (NSTGCTs). Twenty cases of pure seminoma as well as 20 cases of NSTGCTs including 16 mixed germ cell tumours (MGCTs) were studied. Immunohistochemistry for the cytotoxic markers TIA-1 (cytotoxic potential) and granzyme B (cytotoxic activity) and the T-cell markers CD3 and CD8 was performed on formalin-fixed, paraffin-embedded sections. The apoptotic index (AI) was determined by the TUNEL method. The number of CD3(+), CD8(+), TIA-1(+), and granzyme B(+) cells in tumour cell nests was markedly increased in testicular seminomas, compared with NSTGCTs (p<0.01). Activated granzyme B(+) cells numbered 25.6+/-5.2 per high power field in seminomas and 8.9+/-3.2, 8.1+/-3.9, and 0.4+/-0.2 for embryonal carcinomas, yolk sac tumours, and immature teratomas, respectively. Double immunohistochemical staining for granzyme B and CD8 revealed that 82.6+/-8.5% of granzyme B-expressing cells were CD8(+). The tumour cell AI was significantly increased in embryonal carcinoma, compared with the seminoma, yolk sac tumour, and immature teratoma subgroups (6.7+/-1.3, 2.3+/-0.3, 3.0+/-1.1, and 2.3+/-1.1, respectively, p<0.001). TUNEL/CD3 double immunostaining revealed that a significant proportion of the apoptotic seminomatous tumour cells were in direct contact with one or more CD3(+) lymphocytes (47.2+/-6.2%). The number of activated granzyme B(+) CTLs showed a strong linear correlation with the AI in the seminoma group (r=0.71, p<0.0001) but not in other subgroups. TUNEL/granzyme B double immunolabelling revealed that a proportion of activated granzyme B(+) lymphocytes (20%) were often seen in close contact with apoptotic tumour cells. The presence of increased numbers of activated cytotoxic lymphocytes in testicular seminomas suggests that apoptotic tumour cell death in this neoplasm may be triggered by cytotoxic granule effectors. This phenomenon may be one of the key host immune mechanisms leading to the excellent prognosis in this tumour.

Correlation between tumour and serum beta 2m expression in patients with breast cancer

HLA class I antigens are composed of a major histocompatibility complex (MHC) encoded heavy chain that is associated non-covalently with a light chain beta-2 microglobulin (beta-2m). When the HLA complex is metabolized, beta-2m is shed into the serum. A large variety of human and experimental tumours have altered MHC class I expression. In a previous study we observed elevated mean beta-2m serum levels in breast cancer patients, as compared to controls. To study the relationship between tumour expression and serum levels, we examined 54 patients with breast cancer. Tumour beta-2m was determined by immunohistochemistry and serum levels by the ELISA technique. Of the 54 patients, 38 had low and 16 had high beta-2m expression on the tumour. There was a significant correlation between tumour beta-2m and serum beta-2m levels (P = 0.02), with patients whose tumours expressed high beta-2m having high serum beta-2m levels. There was an inverse correlation between tumour grade and tumour beta-2m expression which approached statistical significance (P = 0.06). These findings suggest that in a substantial number of patients the high serum levels derive from shedding of beta-2m from tumour cells. These levels may have implications for tumour growth and metastases due to influences on immunological responses.

HLA class I antigens are expressed by Sertoli cells of intratubular germ cell neoplasia

Five frozen samples from seminomas and one from a combined seminoma/embryonal carcinoma and surrounding tissue were examined for the presence of HLA class I molecules using an antibody directed against a monomorphic epitope of the 45 kDa long chain of HLA-A, -B and -C molecules. Only tubules with intratubular germ cell neoplasia stained positively, while normal seminiferous tubules and invasive tumor cells stained negatively. The immunohistology with anti-HLA class I antibody was compared to that with anti-beta 2-microglobulin antibody which reacts with the light nonpolymorphic chain of all HLA class I molecules. Immunohistology with these two antibodies was indistinguishable. This result combined with immunohistology using anti-PLAP indicates that the stained cells are Sertoli cells. The results are discussed in relation to lymphocytic infiltration and immune surveillance of seminomas.

Sertoli cells of intratubular germ cell neoplasia express beta 2 microglobulin

The cells in intratubular germ cell neoplasia in the vicinity of 38 germ cell tumors of the testis, including 20 pure seminomas, were studied for the expression of beta 2-microglobulin (beta 2m), the constant component of all HLA class I molecules. Immunohistochemistry using antibodies towards beta 2m, vimentin, placental alkaline phosphatase, and ferritin was employed. Whereas the intratubular cells in normal testis are beta 2m negative, beta 2m positive cells were identified in intratubular germ cell neoplasia tubules in 55 per cent of all tumors and in 60 per cent of the seminomas. The tubules with beta 2m positive cells were located in areas with invasive tumor or in the vicinity of such areas. The beta 2m positive cells were identified as Sertoli cells by morphology and by their staining with anti-vimentin. Neoplastic germ cells, identified by morphology and staining with anti-placental alkaline phosphatase and anti-ferritin were beta 2-microglobulin negative. The most intensely beta 2m-stained Sertoli cells were found in tubules with high concentrations of neoplastic germ cells. Intensely stained Sertoli cells were also found in 'Sertoli cell only' tubules inside invasive tumors and in areas without lymphocytic infiltration. The cells in adjacent normal tubules were beta 2m negative.

Assessment of the nucleolar organizer regions by automated image analysis in benign and malignant colonic tumours and adjacent tissues in rats

An automated computer image analysis technique was used to study the morphological parameters of argyrophilic nucleolar organizer regions (AgNORs) in chemically induced rat colonic tumours of different grades. Different nuclear parameters were of different diagnostic value. For distinguishing tumorous tissue from normal tissue all the parameters studied were capable of serving as diagnostic markers. Malignant processes could, however, be more reliably detected by means of the area of the nucleus, nuclear shape factor, area of AgNOR and ratio of AgNOR area to nuclear area. In macroscopically normal tissue adjacent to a tumour, the values of all the AgNOR parameters studied were similar to those in tumorous tissues. It can be concluded that the initial stages in tumorigenesis are accompanied by changes in all of the nucleus and AgNOR parameters, but as malignancy develops, only some of these parameters continue to change. Close correlations between nuclear parameters in malignant tissue suggest that for diagnostic purposes only nuclear and AgNOR areas should be used.

The effect of irradiation on expression of HLA class I antigens in human brain tumors in culture

The immunosuppressive effects of irradiation are well known; however, under certain circumstances irradiation also augments the local immune response by as yet undefined mechanisms. Because of the importance of HLA class I antigen in immune regulation and the fact that killing of tumor cells by cytotoxic T cells is HLA antigen-restricted, the authors studied HLA class I antigen expression in eight glioblastomas multiforme, four meningiomas, and four medulloblastomas. Twenty fragments of each tumor specimen were placed in short-term cultures immediately after resection. For each tumor, control Sample 1 was not irradiated. Sample 2 was irradiated on Day 1, and two groups of the remaining pieces of each tumor (specimens 3 to 10) were irradiated on two consecutive days. Escalating radiation doses were given, starting at 200 cGy/day for Sample 2 up to 1000 cGy/day for Sample 10. The total dose range was 200 to 2000 cGy. Corresponding nonirradiated tumor fragments served as controls. Four hours after irradiation, each sample was processed and stained for HLA class I antigen using the immunoperoxidase technique. The tumor cells were intensely stained in nonirradiated glioblastomas and meningiomas, whereas no staining was observed in medulloblastomas. In four of the eight glioblastomas and in all four meningiomas, irradiation augmented HLA class I antigen expression compared to controls. This effect was dose-dependent and was maximum in the 1200 cGy-treated specimens. No change was observed in the other four glioblastomas or in the medulloblastomas. The data suggest that irradiation does not decrease and may even induce HLA class I antigen expression in some brain tumors. This may be one of the mechanisms by which immunotherapy operates after irradiation. Further studies are required to elucidate optimum radiation doses and fractionation as well as optimum timing of immunotherapy.

Immunohistochemical detection of intercellular adhesion molecule-1 (ICAM-1) and major histocompatibility complex class I antigens in seminoma

Expression of intercellular adhesion molecule-1 (ICAM-1) and major histocompatibility complex (MHC) antigens, and characterization of tumor-infiltrating mononuclear cells (TIM) were examined immunohistologically in 10 specimens of seminoma. ICAM-1 and MHC antigens were not detected on normal spermatogenic cells. ICAM-1 and MHC class I antigens were variably expressed in 7 and 9 seminomas, respectively, whereas class II antigens were not detected. Although the degree of expression of ICAM-1 and MHC antigens was not correlated with any clinical or histopathological factors, neither of the antigens was detected on an anaplastic seminoma. Various numbers of TIM were detected in all of the seminoma, and comprised mainly T cells bearing the lymphocyte function-associated antigen (LFA)-1. No significant correlation was noticed between the degree of lymphocyte infiltration and ICAM-1 or MHC antigen expression. Although ICAM-1 and MHC class I antigens were expressed in seminoma, possibly facilitating an anti-tumor reaction of host, their expression remained low in several cases, despite marked lymphocyte infiltration within the tumor.

Immunological paradox in testicular tumours: the presence of a large number of activated T-cells despite the complete absence of MHC antigens

Tissue sections from 22 seminoma (Se) and 10 teratoma (Te) patients were investigated for correlation between the presence of tumour infiltrating T-lymphocytes (TIL) and the expression of major histocompatibility complex (MHC) antigens using an immunoperoxidase staining technique. Complete absence of both class I and II antigens was observed in all Te and 20 out of 22 Se. The two positive Se showed only weak expression on 2% of tumour cells. Despite the absence of human leucocyte antigens (HLA) there were a large number of TIL scattered throughout the tissues in the case of Se with no predominance of CD4 or CD8 subpopulations in either group. T gamma positive cells were less than 5% of total CD3 positive cells in both Se and Te. The majority of the TIL were found to express activation markers, i.e. HLA class II antigens. Culture of tumour cell suspension with IL-2 produced passageable IL-2-dependent T cells from 10 out of 15 tumours. Studies with testis cell lines showed the complete absence of class I antigens in 2 out of 5 cases and the inability of interferon gamma (IFN gamma) to induce expression. IFN gamma also failed to induce class II antigens in three out of five of these lines. The immunological paradox of the presence of a large number of activated T-cells in testicular tumours despite the complete absence of MHC antigens remains unexplained and needs further investigation. Possible hypotheses are reviewed.

Expression of class I histocompatibility antigens in transitional cell carcinoma of the urinary bladder in relation to survival

The expression of class I histocompatibility antigens (HLA) in transitional cell carcinoma of the bladder was studied by the immunoperoxidase technique and correlated with tumor differentiation and survival. Tumors of 33 patients who underwent cystectomy were examined; 57% of the tumors expressed HLA class I antigens. Positive expression was observed in 5 of 6 cases with Grade 1 tumors, 8 of 13 with Grade 2, and 6 of 14 with Grade 3. The 5-year survival was significantly better in patients with HLA class I-positive tumors (74%) compared with those with negative tumors (36%, P less than 0.05). The expression of HLA class I on tumor cells may serve as a target for the immune response and control the metastatic potential of the tumor. These results suggest that HLA class I expression in bladder carcinoma is a prognostic indicator that should be considered in treatment planning.

Soluble histocompatibility antigen class I in breast cancer patients in relation to tumor burden

Serum beta-2 microglobulin (B-2M) levels were studied in 365 breast cancer patients and 210 age-matched controls. The patients were divided into three groups: Group A, new patients at diagnosis; Group B, patients at follow-up; and Group C, metastatic patients. The mean B-2M of all breast cancer patients plus or minus one standard deviation (3.5 +/- 1.2; range, 1.1 to 5.9) was significantly higher than normal controls (1.29 +/- 0.49; range, 0.3 to 2.3; P less than 0.005). When the three patient groups were compared with each other, the mean B-2M level of Group A (3.0 +/- 1.5; range, 0.9 to 6.9) was similar to that of Group C (4.22 +/- 1.1; range, 2.0 to 6.4). The mean B-2M of both Groups A and C was significantly higher than that of Group B (2.38 +/- 1.02, range, 0.4 to 5.4; P less than 0.001). In Group A the mean B-2M decreased significantly after a 12-month period and reached the mean level of Group B but not that of normal controls. When patients in Group B were analyzed by their stage of disease at diagnosis, there was no significant difference between Stages I and II. There was a significant difference in the mean B-2M levels between Stages I and III. In relapsing patients, mean B-2M levels increased. These findings suggest that serum B-2M levels may reflect tumor burden, and even in patients at follow-up, occult tumor cells may activate the immune system.

Cellular B-2 microglobulin expression as a prognostic indicator in renal cell carcinoma

The expression of B-2 microglobulin (B-2M) on tumor cells and their normal cell counterparts in 39 patients with renal cell carcinoma was studied and correlated to tumor stage and survival. The median survival time of patients with localized disease (stage I) whose tumors expressed B-2M was 10.2 years while the median survival time for patients whose tumors did not express B-2M was only 3.6 years (p less than 0.001). For patients with more advanced disease (stages II, III, IV) whose tumors expressed B-2M, median survival time was 3.6 years compared to 2.0 years in patients whose tumors did not express B-2M, a non-significant difference. It is suggested that the tumor cell membrane expression of B-2M may serve as an indicator of good prognosis in early renal cell carcinoma.