C-type particles are inducible in Se-Ax, a continuous T-cell line from a patient with Sézary's syndrome

Identification of selectively expressed genes and antigens in CTCL

The knowledge of tumor-associated antigens is required for most types of immunotherapy and can substantially facilitate diagnosis. To identify potential tumor-associated genes expressed in cutaneous T-cell lymphoma (CTCL), we used three complementary strategies: antigens which elicit a humoral immune response in CTCL patients were detected by serological analysis of a recombinant cDNA expression library. cDNAs differentially expressed in CTCL but not peripheral blood monocytes were identified by comparative cDNA hybridization and suppression subtractive hybridization. We identified 43 genes selectively expressed by CTCL cells, that have not yet been described in the context of CTCL development, but most of which had been reported to be associated with cancer. Expression analysis by database mining and subsequently RT-PCR on selected clones confirmed their selective expression in CTCL tissues. Serological tests showed that 15 clones were recognized by sera of CTCL patients but not of healthy donors. Analysis of serological tests for 11 clones using serum antibody detection array (SADA) and 100 sera of controls and CTCL patients each revealed up to 5% reactive sera in the tumor group. The expression pattern of the detected clones and their immunogenicity demonstrates that they might be relevant for the understanding of CTCL and suggests particularly three clones, HD-CL-41 (DRAK2), HD-CL-49 (nudC) and HD-CL-12 (ZNF195) for further analysis with respect to their prognostic and therapeutic value for CTCL.

GBP-5 Splicing Variants: New Guanylate-Binding Proteins with Tumor-Associated Expression and Antigenicity

We have identified a new gene, gbp-5, with high homology to the guanylate binding proteins (GBP) belonging to the GTPase superfamily including the ras gene. gbp-5 is transcribed at least into three splicing variants (gbp-5a, -5b, and -5ta) leading to two different proteins (GBP-5a/b, GBP-5ta). GBP-5ta is C-terminally truncated by 97aa and has therefore lost its isoprenylation site. Although RT-PCR results indicated expression of GBP-5 members in selected normal tissues, western blotting using two newly generated antibodies revealed that expression of both proteins is restricted to peripheral blood monocytes with GBP-5ta at lower levels. In contrast, cutaneous T-cell lymphoma (CTCL) tumor tissues (seven of seven) were positive solely for GBP-5ta, and four of four CTCL cell lines expressed both proteins. Eight of nine melanoma cell lines expressed GBP-5a/b and four of nine additionally low levels of GBP-5ta. SEREX retesting using CTCL sera indicated a higher immunogenicity for GBP-5ta (nine of 16) than for GBP-5a/b (two of 11). Treatment of CTCL cell lines with interferon-gamma did not alter protein expression of GBP-5ta or GBP-5a/b. The restricted expression pattern of both GBP-5ta and GBP-5a/b and the pivotal role of many known members of the GTP-binding proteins in proliferation and differentiation suggest possible cancer-related functions of gbp-5.

SEREX identification of new tumour-associated antigens in cutaneous T-cell lymphoma

BACKGROUND

Cutaneous T-cell lymphoma (CTCL) is a clonal lymphoproliferative disorder of mainly CD4+ T cells, with primary manifestation in the skin.

OBJECTIVES

To detect new CTCL-associated antigens for immunological therapies and to define their specificity in terms of RNA expression and seroreactivity.

METHODS

A newly constructed CTCL cDNA phage library was screened and cross-reactivities against the detected clones were tested using 15 mycosis fungoides and six Sézary syndrome sera. The mRNA expression of the identified genes was analysed by reverse transcription-polymerase chain reaction (RT-PCR) using 22 tumour tissues, nine cell lines and up to 29 different types of normal tissue.

RESULTS

We identified nine different tumour antigens (HD-CL-01 to HD-CL-09) of which seven clones had high homology to genes with known functions. Several of these genes had previously been associated with cancer, namely inositol 1,4,5-triphosphate 5-phosphatase, vimentin, aldose reductase and elongation factor-1alpha. Variations in the deduced protein sequences were observed in three cases, mostly due to variations in protein length. The individual clones were recognized by up to 56% of patients' sera, while control sera were negative except in one case. Using RT-PCR, we found a frequent expression of these new tumour antigens in tumour specimens (26-100%). In contrast to humoral specificity, specific mRNA was also detected in selected normal tissues (29-89%).

CONCLUSIONS

SEREX (serological identification of antigens by recombinant expression cloning) identified multiple tumour-associated antigens in CTCL. The serological specificity and the high percentage of reactive sera of CTCL patients against several clones suggest these genes as potential targets for diagnostic and prognostic purposes.

cTAGE: a cutaneous T cell lymphoma associated antigen family with tumor-specific splicing

cTAGE-1 is a cutaneous-T-cell-lymphoma-specific tumor antigen recently identified by serologic identification of antigens by recombinant expression cloning. This study was aimed at identifying and characterizing related genes. Rapid amplification of cDNA ends and DNA screening led to five new members of the cTAGE gene family belonging to four different genes, two of which were differentially spliced (cTAGE-1/2 and cTAGE-5). Expression analysis using reverse transcription polymerase chain reaction revealed that cTAGE-1, cTAGE-1B, and cTAGE-5A expression was restricted to testis and tumor tissues, whereas the other cTAGE members were found in two to eight other normal tissues (of 27 tissues tested). Tumor-specific protein expression of cTAGE-5 was confirmed by Western blotting. Sero-reactivity against cTAGE-1, cTAGE-4, cTAGE-5A, and cTAGE-5B was found only in tumor patients (cutaneous T cell lymphoma and melanoma). The immunogenic epitope of cTAGE-1 was determined by using epitope mapping and sera of two cutaneous T cell lymphoma patients. Moreover, cTAGE-1, cTAGE-4, cTAGE-5A, and cTAGE-5B could be detected in most types of tumor tissues and cell lines at variable frequencies, including those of cutaneous T cell lymphoma, melanoma, head and neck squamous cell carcinoma, breast carcinoma, and colon carcinoma. We conclude that cTAGE-1 and cTAGE-5 are new cancer germline antigens and that tumor-specific splicing of cTAGE genes may lead to further candidate proteins for specific immunotherapy of cutaneous T cell lymphoma and other malignancies.

Tumor-specific antigens in cutaneous T-cell lymphoma: expression and sero-reactivity

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of extra-nodal non-Hodgkin lymphomas with primary manifestation in the skin with poor treatment options in the advanced stages. As basis for future immune-therapeutic strategies we have investigated the possible expression of tumor-specific targets in CTCL focusing mainly on so-called cancer-germline genes. cDNAs derived from 20 CTCL tissues and 4 CTCL cell lines were tested with 15 gene-specific and 4 gene family-specific primers by RT-PCR and confirmative Northern blotting. The most frequently detected mRNAs were LAGE-1 (55% with only partial coexpression of the splicing variants), cTAGE-1 (35%), MAGE-A9 (27%) and the GAGE-3-7 group (35%). Furthermore, we could detect NY-ESO-1 (21%) and a MAGE-A subgroup (15%), whereas sub-specification of the latter proved absence of MAGE-A1, -A2, -A3, -A6 and -A12. SCP-1 was found in only one specimen and a several antigens could not been detected in any tumor tissue or cell line (MAGE-B, GAGE-1,2,8 and all 4 RAGE genes). 90% of all CTCL samples were positive for at least 1 of the frequent mRNAs in RT-PCR (LAGE-1, NY-ESO-1, cTAGE-1, MAGE-A9, or GAGE-3to7). Using a secondary SEREX approach we could detect sero-reactivity in sera of CTCL patients against recombinant cTAGE-1 (10/29), GAGE (3/19), MAGE-A1 (1/18), -A3 (1/18), -A6 (2/18) and -A9 (4/18) protein, but not against LAGE-1a, MAGE-A4b or MAGE-A12 protein (n = 19). We conclude, that certain cancer-germline genes can be detected frequently in CTCL and are able to elicit a systemic immune response. These candidate genes might therefore be promising targets for immunotherapeutic interventions in CTCL.

Serological detection of cutaneous T-cell lymphoma-associated antigens

Cutaneous T-cell lymphomas (CTCL) are a group of skin neoplasms that originate from T lymphocytes and are difficult to treat in advanced stages. The present study is aimed at the identification of tumor-specific antigens from a human testis cDNA library using human sera known as the SEREX (serological identification of recombinantly expressed genes) approach. A cDNA library from normal testicle tissue was prepared and approximately 2 million recombinants were screened with sera from Sézary Syndrome and Mycosis fungoides patients. A total of 28 positive clones belonging to 15 different genes/ORFs were identified, including five hitherto unknown sequences. Whereas control sera did not react with most clones, 11-71% sera from CTCL patients were reactive against the identified clones. Expression analysis on 28 normal control and 17 CTCL tissues by reverse transcription-PCR (RT-PCR) and Northern blotting revealed seven ubiquitously distributed antigens, six differentially expressed antigens (several normal tissues were positive), and two tumor-specific antigens that were expressed only in testis and tumor tissues: (i) A SCP-1-like sequence, which has already been detected in various tumors, has been found in one CTCL tumor and four sera of CTCL patients reacted with various SCP-1-like clones and (ii) a new sequence named cTAGE-1 (CTCL-associated antigen 1) was detected in 35% of CTCL tumor tissues and sera of 6/18 patients reacted with this clone. The present study unravels CTCL-associated antigens independent of the T-cell receptor. The SCP-1-like gene and cTAGE-1 were shown to be immunogenic and immunologically tumor-specific and may therefore be candidates for immunotherapy targeting CTCL.

Serological detection of cutaneous T-cell lymphoma-associated antigens

Cutaneous T-cell lymphomas (CTCL) are a group of skin neoplasms that originate from T lymphocytes and are difficult to treat in advanced stages. The present study is aimed at the identification of tumor-specific antigens from a human testis cDNA library using human sera known as the SEREX (serological identification of recombinantly expressed genes) approach. A cDNA library from normal testicle tissue was prepared and approximately 2 million recombinants were screened with sera from Sézary Syndrome and Mycosis fungoides patients. A total of 28 positive clones belonging to 15 different genes/ORFs were identified, including five hitherto unknown sequences. Whereas control sera did not react with most clones, 11-71% sera from CTCL patients were reactive against the identified clones. Expression analysis on 28 normal control and 17 CTCL tissues by reverse transcription-PCR (RT-PCR) and Northern blotting revealed seven ubiquitously distributed antigens, six differentially expressed antigens (several normal tissues were positive), and two tumor-specific antigens that were expressed only in testis and tumor tissues: (i) A SCP-1-like sequence, which has already been detected in various tumors, has been found in one CTCL tumor and four sera of CTCL patients reacted with various SCP-1-like clones and (ii) a new sequence named cTAGE-1 (CTCL-associated antigen 1) was detected in 35% of CTCL tumor tissues and sera of 6/18 patients reacted with this clone. The present study unravels CTCL-associated antigens independent of the T-cell receptor. The SCP-1-like gene and cTAGE-1 were shown to be immunogenic and immunologically tumor-specific and may therefore be candidates for immunotherapy targeting CTCL.

Genotraumatic T cells and cutaneous T-cell lymphoma. A causal relationship?

Mycosis fungoides, or cutaneous T-cell lymphoma (CTCL), is a T-cell mediated chronic inflammatory skin disease, which can occasionally progress with a variable time course to a fatal lymphoma or to a leukaemic form called Sézary's syndrome. Extensive research into CTCL has not yet elucidated the primary pathophysiological mechanisms. Immunohistological studies are so far less helpful than expected in establishing early diagnosis and prognosis of the disease. The proposition that an exogenous virus is the cause of CTCL has not been substantiated. Karyotypic analysis of lymphocytes from the skin and blood of patients with CTCL have shown the existence of several genetically aberrant T-cell clones in the same patient. These changes are discussed as potential primary events for the development of CTCL. The hypothesis is put forward that the development of genotraumatic T lymphocytes is involved in the progression of the disease.

Retrovirus-like particles in an Epstein-Barr virus-producing cell line derived from a patient with chronic progressive myelopathy

A B-lymphoblastoid cell line (LCL) of polyclonal origin was isolated from a 30-year-old male patient with a chronic progressive myelopathy clinically resembling multiple sclerosis (MS). The LCL expresses Epstein-Barr virus (EBV) encoded proteins and on transmission electron microscopy (EM) the LCL was shown to produce both EBV particles and retrovirus-like particles spontaneously. The LCL was negative for human retrovirus (HIV-I and HTLV-I) sequences by polymerase chain reaction (PCR). Furthermore the patient was seronegative to these retroviruses including HTLV-II and HIV-II. We, therefore, suggest that the LCL is double-infected with EBV and a hitherto uncharacterized human retrovirus. The possible implications of these two viruses on development of diseases are discussed.

Antibodies against retroviral core proteins in relation to disease outcome in patients with mycosis fungoides

We have studied the relationship of antibodies reacting with human retroviral core proteins to the disease outcome in Finnish mycosis fungoides (MF) patients in a prospective manner. Antibodies recognizing human T-cell leukaemia/lymphoma virus I (HTLV-I) or human immunodeficiency virus type 1 (HIV-1) core proteins were found in 12 of 14 MF patients as shown by the Western blot method. The antibody reactivities showed three patterns: three patients had antibodies cross-reacting with the gag-encoded core proteins of both HTLV-I and HIV-1; seven patients showed antibodies reacting with HTLV-I core proteins only; and the sera of two patients reacted with HIV p24 core protein only. When following the clinical course of these patients, we found that the three patients with antibodies cross-reacting with both viruses had the most fulminant clinical course, and the overall duration of MF was, on average, 4 years less than in the rest of the patients. None of the patients, however, became leukaemic, or showed any other features suggestive of acute T-cell leukaemia/lymphoma (ATL). Two patients, who did not show anti-retroviral antibodies during the follow-up, had a stable disease with plaque-type skin lesions. Histological or immunohistological typing of the skin infiltrates did not correlate with the disease outcome or the above antibody patterns. Our results thus raise the possibility that an unknown retrovirus, immunologically related to the known human retroviruses, may be aetiologically linked to MF.