High frequency of allele-specific down-regulation of HLA class I expression in uveal melanoma cell lines

Uveal melanoma is the most common primary intra-ocular tumor in adults and has a high mortality rate due to liver metastases, for which no effective treatment is available. To investigate whether immunotherapy might be feasible in uveal melanoma, the HLA class I surface expression of 6 uveal melanoma cell lines was analyzed by flow cytometry using a broad panel of allele-specific monoclonal antibodies. To up-regulate HLA expression, cells were also cultured with IFN-alpha or -gamma. In general, expression of HLA-A alleles was high (except for cell line EOM-3) and could be further up-regulated by both IFN-alpha and -gamma. In cell line EOM-3, IFN-gamma treatment resulted in significant HLA-A expression while IFN-alpha treatment did not. Expression of HLA-B alleles was low or even negative. Variable effects were observed after IFN treatment. In 3 cell lines, expression of some HLA-B alleles could not be induced by IFN-alpha or -gamma: HLA-B44 in cell line 92-1, HLA-B15 in cell line OCM-1 and HLA-B5 in cell line MEL-202. The other B alleles of these cell lines showed enhanced expression levels upon IFN stimulation. In OMM-1 cells, IFN-alpha and -gamma increased the expression of HLA-A but did not induce expression of the 2 B alleles, indicating an HLA-B locus-specific loss. We thus found a high frequency of allele-specific and locus-specific down-regulation of HLA expression in uveal melanoma cell lines. Some of these defects were not restored by IFN-alpha or -gamma treatment. The lack of HLA expression may explain why uveal melanoma cells escape immune surveillance by cytotoxic T cells and complicate the development of immunotherapy in uveal melanoma.     

Cell phenotype dependent expression of MHC class I antigens in Burkitt's lymphoma cell lines.

Burkitt's lymphoma (BL) is a highly malignant B cell tumor characterized by three types of chromosomal translocation which constitutively activate the c-myc oncogene by juxtaposing it to Ig coding sequences. Epstein-Barr virus (EBV) infection, hyperendemic malaria and HIV-caused immunosuppression are thought to contribute to the pathogenesis of the tumor. Cell lines derived from EBV carrying and EBV negative BLs often show altered MHC class I antigen expression. The defects include a lower expression of all HLA class I antigens compared to EBV transformed normal B-blasts, and selective down-regulation of certain HLA-A and HLA-C alleles. As a consequence BL cells are often resistant to cytotoxic T lymphocyte (CTL) mediated destruction. Alleles selective down-regulations are found only in cell lines that maintain the tumor cell phenotype while shift towards a more activated 'B-blast like' phenotype is accompanied by HLA class I up-regulation. A similar pattern of HLA class I expression can be found in a subpopulation of germinal center B cells which express a 'BL like' phenotype. Our findings suggest that the HLA class I expression of BL cells reflects the characteristics of the normal B cell precursor and is probably not the result of immune selection.     

HLA class I antigen down-regulation in primary ovary carcinoma lesions: association with disease stage.

PURPOSE: To investigate TAP1, TAP2, and HLA class I antigen expression in primary ovarian carcinoma lesions and to assess the clinical significance of defects in the expression of these molecules. EXPERIMENTAL DESIGN: Fifty-one formalin-fixed, paraffin-embedded primary ovarian carcinoma lesions were stained with affinity-purified rabbit anti-TAP1 and anti-TAP2 antibodies and with anti-HLA class I heavy chain monoclonal antibody (mAb) HC-10 using the immunoperoxidase reaction. The results of immunohistochemical staining were correlated with the histopathologic characteristics of the lesions and with patients' survival. RESULTS: Ovarian surface epithelium, thecal cells of follicles, and stromal cells were stained by anti-TAP1, anti-TAP2, and anti-HLA class I antigen xenoantibodies with a homogeneous pattern. In contrast, no staining of lutheinic cells by these antibodies was detected. Forty-one and 32 out of 51 primary ovarian carcinoma lesions were stained by anti-TAP1 and anti-TAP2 xenoantibodies and by anti-HLA class I antigen mAb HC-10, respectively. The staining patterns by anti-TAP1 and anti-TAP2 xenoantibodies were completely concordant, but did not correlate with that by anti-HLA class I heavy chain mAb HC-10. TAP1 and TAP2 expression was associated neither with the histopathologic characteristics of the lesions nor with clinical variables. On the other hand, HLA class I antigen down-regulation was associated with disease stage: the odds ratio of stage III for HLA class I antigen negative patients was 7.6 (95% confidence interval, 1.9-30.5; P= 0.007), whereas for TAP negative patients was 5.1 (95% confidence interval, 0.9-28.4; P = 0.07). Follow up was available for 39 out of the 51 patients. Multivariate analysis showed that both grading and staging were associated with a higher risk of death, whereas TAP and HLA class I antigen phenotypes were not. CONCLUSIONS: The lack of association between TAP and HLA class I antigen expression is compatible with the possibility that multiple mechanisms underlie HLA class I antigen down-regulation in primary ovarian carcinoma lesions. The potential role of immunologic events in the clinical course of ovarian carcinoma suggests that the association between HLA class I antigen down-regulation and disease progression may reflect the escape of tumor cells from immune recognition and destruction.     

Loss or down-regulation of HLA class I expression at the allelic level in freshly isolated leukemic blasts

Loss or down-regulation of human leukocyte antigen (HLA) class I expression has been demonstrated in a variety of solid tumors. To date, such altered HLA expression has not been studied extensively in freshly isolated leukemic blasts. If it occurs, leukemic cells could escape T-cell surveillance as a consequence. Genotypes of nine leukemic cell lines were determined using a polymerase chain reaction for HLA classes I and II. Cells were also examined for HLA beta2-microglobulin, and allele-specific HLA protein expression using flow cytometry. Next, 44 samples of freshly isolated leukemic blasts from 43 patients with malignant hematological diseases were examined for allele-specific HLA expression using flow cytometry. Microsatellite analysis was performed to determine heterozygosity in the HLA region on chromosome 6. Genotype analysis for HLA class I together with microsatellite analysis demonstrated loss of HLA haplotype in HL-60 cells. No loss of HLA haplotype was observed in 44 samples of freshly isolated leukemic blasts. As reported previously, flow cytometric analysis rarely demonstrated loss or down-regulation of HLA expression at initial diagnosis (3/39; 7.7%); however, this was evident in two of five cases in relapse (40.0%), which contrasts with previous reports. In one patient with acute leukemia, HLA-A2 cell surface expression was present at initial diagnosis, lost at relapse, and completely restored after 48 h of culture in the presence of interferon-gamma. These results suggest loss of allele-specific HLA expression may be involved in the pathogenesis of relapse in patients with leukemia. The findings should be valuable in designing new strategies for clinical immunotherapy.     

HLA class I antigen down-regulation in primary laryngeal squamous cell carcinoma lesions as a poor prognostic marker

We have investigated the role of antigen-processing machinery (APM) component defects in HLA class I antigen down-regulation in laryngeal squamous cell carcinoma (SCC) lesions and assessed the clinical significance of these defects. To this end, 63 formalin-fixed, paraffin-embedded tumor lesions were examined for APM component and HLA class I antigen expression by immunohistochemistry. Calnexin, calreticulin, and ERp57 were down-regulated in approximately 25% of the lesions tested, whereas LMP2, TAP1, tapasin, and HLA class I antigens were down-regulated in at least 70% of the lesions tested. LMP2 and tapasin expression was significantly correlated with HLA class I antigen expression suggesting APM component defects as a mechanism underlying HLA class I antigen down-regulation in laryngeal SCC lesions. The expression of most APM components and HLA class I antigens was correlated with the extent of CD8+ T cell infiltration into tumor lesions. Furthermore, LMP2 and HLA class I antigen down-regulation and low CD8+ T cell infiltration were significantly associated with reduced patients' survival. Multivariate analysis identified HLA class I antigen down-regulation as an independent unfavorable prognostic marker. This association is likely to reflect the reduction in the extent of CD8+ T cell infiltration in laryngeal SCC lesions.     

Burkitt's lymphoma in Europe

Burkitt's lymphoma (BL) is the most frequent childhood non-Hodgkin's malignant lymphoma (NHML) in Europe and accounts for 5 to 10% of adult NHML. Age distribution is similar to that of endemic BL, with a male:female ratio of 3.7:1. Epstein-Barr virus (EBV) association is found in 15% of cases. A better definition of this monoclonal B-cell malignant proliferation is cytogenetic (i.e., 8;14 or variant translocation). Abdominal masses are initially present in 70% of cases, whereas the jaw is involved in only 4%. The disease is characterized by its overwhelming evolution in the absence of therapy. However, complete remission is usually obtained after the first chemotherapy regimen. In the past, death has been related to cerebrospinal fluid involvement, local recurrence or secondary marrow involvement. Today, it is expected that more than 80% of BL cases will be cured, i.e., 100% of stages I and II abdominal, 70% of stage II non-abdominal and stage III, and 50% of stage IV. Ninety percent of patients alive with no evidence of disease eight months after complete remission can be considered as definitively cured.     

Burkitt's lymphoma in Japan

The clinicopathological features of 18 Japanese patients with Burkitt's lymphoma are reviewed. Six patients were 12 years of age or younger. Seven patients presented with abdominal masses and seven with jaw tumours. Thirteen patients manifested blood and/or marrow involvement at the time of initial diagnosis (five patients) or later in the course of the disease (eight patients). Most of the patients had a rapid clinical course in spite of combination chemotherapy. The malignant cells from all 17 patients examined exhibited a B-cell phenotype; the surface immunoglobulin was IgM in 15 and IgG in two. Two patients had tumours positive for Epstein-Barr virus-determined nuclear antigen while the other 13 patients tested lacked this antigen in their tumours. Chromosome analysis revealed a t(8;14) translocation in 11 patients, a 14q+ without an identifiable donor chromosome in two, a t(2;8) translocation in two, and a t(8;22) translocation in one.     

Identification of HLA class I dependent immunogenic peptides from clonotypic TCRbeta expressed in cutaneous T-cell lymphoma

The clonotypic T-cell receptor (TCR) is a potential target antigen for specific immunotherapy of cutaneous T-cell lymphoma (CTCL). We identified T-cell epitopes from the rearranged TCR beta chain of the malignant T-cell population by the "reverse immunology" approach. Peptide-specific T-cell lines were generated against predicted epitopes and tested for the recognition of tumor cells and cells transfected with the full-length DNA coding for TCRV beta chain. Two peptides derived from the clonotypic TCRVbeta of a HLA-A2 positive patient could induce peptide-specific T cells from peripheral blood mononuclear cells of healthy donors and the patient as assessed by IFN-gamma ELISpot assay. Furthermore, the reactive CTLs efficiently recognized autologous Sézary tumor cells, as well as HLA-A2 positive 293 cells transfected with recombinant plasmid expressing the corresponding TCRVbeta29 protein. Similar results were obtained in a HLA-A3+ patient for TCRVbeta7-Jbeta2.7. In conclusion, our experiments show that the TCR beta chain harbors epitopes suitable as targets for specific vaccination which might be a promising approach for the specific immunotherapy of cutaneous T-cell lymphoma patients.     

Defective presentation of MHC class I-restricted cytotoxic T-cell epitopes in Burkitt's lymphoma cells

Defects of antigen processing/presentation have been suggested to play a role in the escape of Burkitt's lymphoma (BL) from cytotoxic T lymphocyte (CTL)-mediated rejection. Impaired presentation of an immunodominant HLA AII-restricted epitope from the resident or recombinant vaccinia virus-expressed Epstein-Barr virus nuclear antigen (EBNA)4 was demonstrated in the EBV-positive E95B-BL28 and its EBV-negative parental BL28 cell lines. We have investigated whether this was due to (i) impaired production of the antigenic peptide, (ii) poor peptide translocation into the ER lumen or (iii) inefficient maturation and transport of the MHC-peptide complexes at the cell surface. The defect was not overcome by cytosolic expression of a pre-formed epitope, suggesting that presentation of EBNA4 is not limited by inefficient production of the antigenic peptide. BL28 expressed 5- to 10-fold lower levels of the transporter associated with antigen presentation (TAP) 1 and TAP2 proteins and behaved poorly in a streptolysin-O-mediated peptide translocation assay, whereas E95B-BL28 showed higher TAP expression and virtually normal transporter function. Up-regulation of HLA AII and reconstitution of TAP activity by treatment with IFN-γ did not restore presentation of the resident EBNA4 in E95B-BL28 and did not enhance presentation of the vaccinia virus-expressed intact protein or preformed epitope. Efficient maturation of class I molecules to Endo H-resistant species was demonstrated in pulse-chase experiments. Taken together, our findings identify a previously uncharacterized defect of antigen presentation which appears to affect events occurring after proteasomal degradation but before TAP-dependent peptide transport and MHC class I assembly and maturation. © 1996 Wiley-Liss, Inc.     

Relapse in Burkitt's lymphoma.

Of 109 patients with histologically confirmed Burkitt's lymphoma who completed a course of chemotherapy, 86 (79%) achieved complete remission. Forty-five (52%) of patients with initial complete remission relapsed with tumour over an observation period ranging from 2 years to over 5 years. Relapse was more common in patients who initially presented with abdominal or central nervous system (CNS) involvement than in patients who presented with localized facial tumours (p less than 0.01). Anatomical distribution of tumour on relapse differed from that at presentation. Facial bones were much less frequently involved on relapse; on the other hand, the CNS, cranial nerves, orbits and skin were frequent sites of disease on relapse. CNS involvement occurred in 42% (19/45) of patients at the first relapse and in 73% (11/15) of patients with multiple relapses. Prognosis in these patients was poor. Two relapse types were clinically identifiable. Early relapse (remission duration less than 12 weeks) was associated with frequent involvement of the CNS, drug resistance and a generally unfavourable outcome. Patients with late relapse (remission duration greater than 12 weeks) responded much better to secondary treatment. Possible pathogenic mechanisms underlying these two relapse types are discussed.     

Primary CNS lymphoma and HLA class I and II alleles in a German cohort of immunocompetent patients

Human leukocyte antigens (HLA) are involved in the regulation of immune response to infection and in malignant transformation. Several HLA alleles are associated with immunological or malignant diseases. The aim of the present study was to evaluate a potential association of HLA class I and II alleles with primary central nervous system lymphoma (PCNSL) in immunocompetent patients. We therefore analyzed particular HLA-A, HLA-B and HLA-DRB1 alleles in 82 PCNSL patients and compared the data to those in 327 population controls. No significant difference between these two groups was found using Pearson's chi(2) test. These data do not support the hypothesis that HLA alleles play a major role in the pathogenesis of PCNSL.     

Spinal Burkitt's lymphoma in adults

Adult Burkitt's lymphoma is an uncommon disease. Few cases of spinal involvement in adults with sporadic Burkitt's lymphoma are reported in the literature. We present a case of a middle-aged man who was found to have an epidural mass in the thoracic spine when investigated for back pain and lower extremity weakness. He underwent a laminectomy with resection of the epidural mass. Histologic examination revealed a primary Burkitt's lymphoma of the spinal cord. He was treated with aggressive chemotherapy and is now experiencing remission of his disease. We also present a review of the literature for the etiology and clinical features of other spinal lymphomas and Burkitt's lymphoma involving the spine in adults.     

Burkitt's lymphoma and malaria

The distribution of Burkitt's lymphoma is related to endemicity of malaria, not only on a world-wide basis, but also in more detailed studies in East Africa, particularly in Uganda. This geographical association, together with the diminished incidence of AS haemoglobulin in patients with this tumour and the increased susceptibility to lymphoma formation in mice infected with chronic malaria, suggest a causal relationship.