All infiltrating T-lymphocytes in Hodgkin's disease express immunohistochemically detectable T-cell receptor zeta-chains in situ

Suppression of T cell responses in the tumor microenvironment

The immune system recognizes protein antigens expressed in transformed cells evidenced by accumulation of antigen-specific T cells in tumor and tumor draining lymph nodes. However, despite demonstrable immune response, cancers grow progressively suggesting that priming of antitumor immunity is insufficiently vigorous or that antitumor immunity is suppressed, or both. Compared to virus infection, antitumor T cells are low abundance that likely contributes to tumor escape and enhancement of priming is a long-sought goal of experimental vaccination therapy. Furthermore, patient treatment with antigen-specific T cells can in some cases overcome deficient priming and cause tumor regression supporting the notion that low numbers of T cells permits tumor outgrowth. However, tumor-induced suppression of antitumor immune response is now recognized as a significant factor contributing to cancer growth and reversal of the inhibitory influences within the tumor microenvironment is a major research objective. Multiple cell types and factors can inhibit T cell functions in tumors and may be grouped in two general classes: T cell intrinsic and T cell extrinsic. T cell intrinsic factors are exemplified by T cell expression of cell surface inhibitory signaling receptors that, after contact with cells expressing a cognate ligand, inactivate proximal T Cell Receptor-mediated signal transduction therein rendering T cells dysfunctional. T cell extrinsic factors are more diverse in nature and are produced by tumors and various non-tumor cells in the tumor microenvironment. These include proteins secreted by tumor or stromal cells, highly reactive soluble oxygen and nitrogen species, cytokines, chemokines, gangliosides, and toxic metabolites. These factors may restrict T cell entrance into the tumor parenchyma, cause inactivation of effector phase T cell functions, or induce T cell apoptosis ultimately causing diminished cancer elimination. Here, we review the contributions of inhibitory factors to tumor T cell dysfunction leading to tumor escape.

Signaling defects in anti-tumor T cells

The immune response to cancer has been long recognized, including both innate and adaptive responses, showing that the immune system can recognize protein products of genetic and epigenetic changes in transformed cells. The accumulation of antigen-specific T cells within the tumor, the draining lymph node, and the circulation, either in newly diagnosed patients or resultant from experimental immunotherapy, proves that tumors produce antigens and that priming occurs. Unfortunately, just as obviously, tumors grow, implying that anti-tumor immune responses are either not sufficiently vigorous to eliminate the cancer or that anti-tumor immunity is suppressed. Both possibilities are supported by current data. In experimental animal models of cancer and also in patients, systemic immunity is usually not dramatically suppressed, because tumor-bearing animals and patients develop T-cell-dependent immune responses to microbes and to either model antigens or experimental cancer vaccines. However, inhibition of specific anti-tumor immunity is common, and several possible explanations of tolerance to tumor antigens or tumor-induced immunesuppression have been proposed. Inhibition of effective anti-tumor immunity results from the tumor or the host response to tumor growth, inhibiting the activation, differentiation, or function of anti-tumor immune cells. As a consequence, anti-tumor T cells cannot respond productively to developmental, targeting, or activation cues. While able to enhance the number and phenotype of anti-tumor T cells, the modest success of immunotherapy has shown the necessity to attempt to reverse tolerance in anti-tumor T cells, and the vanguard of experimental therapy now focuses on vaccination in combination with blockade of immunosuppressive mechanisms. This review discusses several potential mechanisms by which anti-tumor T cells may be inhibited in function.

Alterations in the expression pattern of TCR zeta chain in T cells from patients with hematological diseases

The TCR zeta chain, a component of the T cell receptor (TCR)/CD3 complex, plays a significant role in the assembly of the receptor complex and in connecting antigen recognition to the intracellular signal transduction apparatus. Recently, studies have demonstrated altered expression and function of this signal transduction molecule in T cells from patients with hematological diseases. In this review, current knowledge concerning the biological feature and function of TCR zeta protein, splice variant and mutation of TCR zeta chain gene and alteration of expression pattern in hematological diseases and the related mechanism are summarized.

Decreased expression of CD28 coincides with the down-modulation of CD3zeta and augmentation of caspase-3 activity in T cells from hepatocellular carcinoma-bearing patients and hepatitis C virus-infected patients

BACKGROUND AND AIM

Hepatitis C virus (HCV) infection causes chronic inflammation and increases the risk of hepatocellular carcinoma (HCC). This immunosuppressive state may be one reason why HCV-infected patients often have multicentric cancers. Therefore, the purpose of the present study was to assess the cellular immune function in HCC-bearing and HCV-infected patients.

METHODS

The expression of cluster of differentiation (CD)3zeta, CD28 and caspase-3 activity of peripheral blood T lymphocytes (PBL) from HCC-bearing patients, HCV-infected patients and normal subjects was measured by flow cytometric methods. Furthermore, intrahepatic T lymphocytes (IHL) and tumor-infiltrating T lymphocytes (TIL) from HCC patients were used.

RESULTS

Decreased expressions of CD3zeta, CD28 and the augmentation of caspase-3 activity were recognized in PBL from HCC and HCV patients. These phenomena were more dominant in TIL and IHL than in PBL in HCC patients. Furthermore, the down-modulation of CD3zeta and increased caspase-3 activity occurred in CD28 down-modulated T cells.

CONCLUSION

These results demonstrate impairment of the cellular immune system in HCC and HCV patients from the viewpoints of the down-modulation of CD3zeta and CD28 on T cells and T-cell apoptosis. In addition, the results imply that the down-modulation of CD3zeta and T-cell apoptosis take place in activated T cells.

T-cell-rich B-cell lymphoma - diagnostic and therapeutic aspects

BACKGROUND

Morphologically, T-cell-rich B-cell lymphoma (TCRB-NHL) may be indistinguishable from Hodgkin's disease (HD). Immunophenotyping may be helpful in the separation of these entities. TCRB-NHL is occasionally misdiagnosed and treated as HD. However, information is limited regarding clinical characteristics and outcome of this patient population. Furthermore, knowledge concerning any association with Epstein-Barr virus (EBV) in TCRB-NHL, as well as the immunophenotype of reactive T-cells and the expression of T-cell intracellular antigen-1 (TIA-1), granzyme B (GrB) and the CD3-zeta-chain is limited.

PATIENTS AND METHODS

We have re-evaluated 251 tumour biopsies from patients aged > or =15 years with HD diagnosed 1985-1994. Reclassification from HD to TCRB-NHL was done in 12 cases (5%). Six TCRB-NHL patients initially diagnosed and treated as B-NHL were also included. All TCRB-NHL biopsies were analysed for latent membrane protein 1 (LMP-1), CD4, CD8, CD56, CD57, TIA-1, GrB and CD3-zeta-chain.

RESULTS

Twelve cases of TCRB-NHL were initially subclassified as HD (lymphocyte predominance 5, nodular sclerosis 3, and mixed cellularity 4). Of these 12 TCRB-NHL patients, 6 were given radiotherapy alone, 5 MOPP/ABVD or similar combination chemotherapy, and one patient combined modality treatment. Male sex (p<0.05) and inguinal involvement (p<0.001) were significantly more frequent when TCRB-NHL patients receiving HD treatment (n=12) were compared with the remaining patients with confirmed (conf) HD, while no significant differences were seen with regard to stage, bone marrow infiltration, splenomegaly or cause-specific survival. Similar results were achieved when all TCRB-NHL patients (n=18) were compared to conf HD patients. Lymphoma cells in three samples stained positively for LMP-1. A decreased expression of CD3-zeta-chain was seen in 9/14 tumour biopsies.

CONCLUSION

Immunohistochemistry makes it possible to identify cases of TCRB-NHL that are morphologically difficult to distinguish from HD. The outcome of TCRB-NHL patients treated as having HD was comparable with that of the remaining HD population.

Follicle-stimulating hormone receptors in oocytes?

The regulatory mechanisms of oocyte maturation remain poorly understood. Although gonadotropins play a major role in these processes, they have generally been considered to act on somatic supportive cells, but not directly on germ cells. We have raised high affinity monoclonal antibodies against LH and FSH receptors. When using the latter to study receptor distribution in human and pig ovaries we have observed the presence of FSH (but not LH) receptors in the oocytes. FSH receptors appeared in the oocytes of primary follicles during follicular development and persisted up to the preovulatory stage. In denuded human preovulatory oocytes, FSH receptor mRNA was detected at a concentration per cell exceeding by about 20-fold that present in granulosa cells. Saturable binding of [(125)I]FSH to the membrane of oocytes was demonstrated by autoradiography. When incubated with FSH, denuded oocytes responded by a mobilization of Ca(2+). These observations concur to demonstrate the presence of functional FSH receptors in oocytes and raise the possibility of direct control of oocyte development by FSH.

Expression of the signal transduction molecule zeta in peripheral and tumour-associated lymphocytes in Hodgkin's disease in relation to the Epstein-Barr virus status of the tumour cells

We investigated whether the described immune evasion of Epstein-Barr virus (EBV)-infected malignant Hodgkin and Reed-Sternberg (HRS) cells in Hodgkin's disease (HD) is paralleled by a disturbed expression of the signal transduction molecule zeta associated with CD3 and CD16 in tumour-associated T lymphocytes (TAL). Flow cytometric analysis revealed a significantly lower zeta expression in CD3+/4+, CD3+/8+ and CD16+ patient peripheral blood lymphocytes (PBL; n = 10) compared with normal donor PBLs (n = 11). When patient PBLs were compared with the corresponding TAL, the latter showed a significantly higher (CD3+/4+) or equal (CD3+/8+) zeta expression. The EBV status of the tumours did not correlate with zeta expression in the TAL. Immunohistochemical staining revealed zeta-positive lymphocytes among the adjacent bystander cells of the HRS cells in all analysed tumours (n = 8), irrespective of tumour EBV status. In conclusion, these results do not support downregulation of zeta in TAL as a critical mechanism contributing specifically to the immune escape of EBV+ HRS cells.

Tissue eosinophilia in relation to immunopathological and clinical characteristics in Hodgkin's disease

Eosinophils frequently infiltrate tissues involved by Hodgkin's disease (HD), and blood eosinophilia is frequently observed. However, the clinical significance and the mechanisms underlying eosinophilia need further elucidation. In this study the grade of eosinophilic infiltration (EoI) was evaluated in biopsies from 259 HD-patients. In a selected group (n=32), the numbers of Hodgkin-Reed-Sternberg (HRS)-cells were counted, and the phenotype of small lymphocytes, the expression of cytotoxic lymphocyte-associated proteins, CD3-zeta-chain, HLA-DR, proliferation markers, latent membrane protein 1 (LMP-1) and blood lymphocyte function were evaluated. Samples from 88 HD patients (34%) showed high EoI. Significantly higher EoI was seen in nodular sclerosis 2 (NS2; p<0.001), bulky disease (p<0.05) and in patients <50 years (p<0.05). Patients with high EoI did not differ from the remainder with regard to distribution of sex, stage, B-symptoms, blood lymphocyte function and outcome. HRS-cells were significantly more frequent in NS HD as compared to mixed cellularity (MC) (p<0.001) irrespective of EoI. LMP-1-expression, proliferative fraction and phenotypes of small lymphocytes did not differ between the cases with low and high EoI, respectively. MC HD samples had significantly higher numbers of small cells positive for CD8 (p<0.01), T-cell intracellular antigen-1 (p<0.01) and Granzyme B (p<0.05) than NS. LMP-1-positive cases had significantly higher frequency of CD8-positive cells than LMP-1-negative. In conclusion, high EoI remains a feature of certain clinical subgroups of HD. However, there was no association between the degree of EoI and numbers of HRS-cells, phenotypes of small lymphocytes, EBV status and clinical outcome. Determination of EoI is of limited diagnostic and prognostic clinical value in HD. However, the differences in small cell distribution of CD8, TIA-1, GrB and CD57 between the histopathological groups and between LMP-1-expressing/non-expressing cases may contribute to our understanding of the biology of the disease.

Expression of human tumor-associated antigen RCAS1 in Reed-Sternberg cells in association with Epstein-Barr virus infection: a potential mechanism of immune evasion

RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) is present in neoplastic cells, induces apoptosis of natural killer (NK)/T cells and plays a role in immune evasion. Fas ligand (FasL) is considered to have similar roles. The Epstein-Barr virus (EBV)-encoded latent membrane protein is expressed by malignant Hodgkin and Reed-Sternberg (H&RS) cells of EBV-associated Hodgkin's disease (HD) and considered to be a target of cytotoxic T lymphocytes (CTLs). However, CTL response is inadequate in HD. To determine whether RCAS1 and FasL are expressed in EBV-associated HD and participate in immune evasion, tissues of 20 EBV(-) and 15 EBV(+) HD cases were immunohistochemically stained for RCAS1, FasL and HLA classes I and II, whose deficiencies could explain CTL escape. Lymphocytes surrounding H&RS cells tended to be CD4(+) cells and rarely CD8(+), TIA-1(+) (cytotoxic marker) or NK cells. HLA class I and/or II were expressed in all EBV(+) HD cases, and RCAS1-expressing H&RS cells were found in 14/15 (93%) EBV(+) HD cases but only 8/20 (40%) EBV(-) HD cases (p < 0.05). FasL was detected in 9/15 (60%) and 7/20 (35%) EBV(+) and EBV(-) HD cases, respectively. ssDNA-positive (apoptotic) lymphocytes, surrounding H&RS cells, were rarely seen but were present in RCAS1(+) cases (20/22 cases, 91%) rather than negative cases (0/13 cases, 0%) (p < 0.005). Our findings suggest that EBV(+) H&RS cells might evade the host immune response by expressing RCAS1 rather than FasL.