Clonal dominance of human autologous cytotoxic T lymphocytes against gastric carcinoma: molecular stability of the CDR3 structure of the TCR alphabeta gene

A new approach to simultaneously quantify both TCR α- and β-chain diversity after adoptive immunotherapy

PURPOSE

T-cell receptor (TCR) variable Vα and Vβ gene diversity is a surrogate biomarker for the therapeutic potential of adoptive immunotherapy and cellular immunity. Therefore, creating a straightforward, rapid, sensitive, and reliable method to view the global changes of both TCRVα and Vβ transcripts in heterogeneous populations of T cells is appealing.

EXPERIMENTAL DESIGN

We designed a "direct TCR expression assay" (DTEA) using a panel of customized bar-coded probes that simultaneously detects and quantifies 45 Vα and 46 Vβ transcripts in a nonenzymatic digital multiplexed assay from a small number of cells (10(4) cells) or as little as 100 ng of total RNA.

RESULTS

We evaluated DTEA on total RNA samples of tumor-infiltrating lymphocytes and peripheral blood obtained from patients with melanoma after adoptive T-cell therapy. DTEA detected a similar spectrum of the dominant patterns of TCRVβ gene usage as sequencing cloned TCRVβ CDR3 regions. However, DTEA was rapid, achieved a level of sensitivity to identify rare T-cell populations, and simultaneously tracked the full array of Vα and Vβ transcripts.

CONCLUSIONS

DTEA can rapidly and sensitively track changes in TCRVα and Vβ gene usages in T-cell pools following immune interventions, such as adoptive T-cell transfer, and may also be used to assess impact of vaccination or reconstitution of T-cell compartment after hematopoietic stem cell transplantation.

Regional variation of the alphabeta T cell repertoire in the colon of healthy individuals and patients with Crohn's disease

Clonally expanded T cells might be involved in the pathogenesis of Crohn's disease (CD). To test the impact of CD on the regional distribution of expanded T cells, this study analyzed the T cell receptor beta (TCRB) repertoire within colonic biopsy specimens from 12 CD patients and 6 noninflammatory controls by TCR spectratyping. Migration characteristics of dominant CDR3 bands from different sites of the normal mucosa suggested focal, segmental, or ubiquitous spreading of individual expanded clones. Similar patterns were observed when inflamed and noninflamed areas of the colon of CD patients were compared, suggesting that regional expansion of T cells was more closely related to anatomic proximity than to local inflammatory activity. CDR3-sequence analysis of TCRBV12+ T cells, which were selectively expanded in the inflamed colon of 3 CD patients, failed to reveal a public CDR3 motif. Our data indicate the existence of distinct patterns of regional T cell expansions in the normal gut mucosa, which are not significantly disrupted by chronic intestinal inflammation. This does not exclude a pathogenic role of expanded T cells in CD through more subtle changes, but emphasizes the need to distinguish them from a discontinuous distribution of clonally expanded T cells in normal colon.

The prognostic advantage of preoperative intratumoral injection of OK-432 for gastric cancer patients

To investigate, by a multi-institutional randomized trial, the prognostic significance of the augmentation of tumour-infiltrating lymphocytes (TILs) by preoperative intratumoral injection of OK-432 (OK-432 it), a bacterial biological response modifier, in patients with gastric cancer. The 10-year survival and disease-free survival were examined and analysis of the factors showing survival benefit was performed. 370 patients who had undergone curative resection of gastric cancer were enrolled in this study and followed up for 10 years postoperatively. Patients were randomized into either an OK-432 it group or a control group. Ten Klinishe Einheit (KE) of OK-432 was endoscopically injected at 1 to 2 weeks before the operation in the OK-432 it group. Both groups received the same adjuvant chemoimmunotherapy consisting of a bolus injection of mitomycin C (0.4 mg kg(-1) i.v.) and administration of tegafur and OK-432 from postoperative day 14 up to 1 year later. Tegafur (600 mg day(-1)) was given orally and OK-432 (5 KE/2 weeks) was injected intradermally for a maintenance therapy. The TILs grades in resected tumour specimens and presence of metastasis and metastatic pattern in dissected lymph nodes were examined. Multivariate analysis was performed to determine the efficacy of OK-432 it on prognostic factors. All patients were followed up for 10 years. The overall 5- and 10-year survival rates and disease-free survival rates of the OK-432 it group were not significantly higher than those of the control group. However, OK-432 it significantly increased the 5- and 10-year survival rates of patients with stage IIIA + IIIB, moderate lymph node metastasis (pN2), and positive TILs. OK-432 it was most effective at prolonging the survival of patients who had both positive TILs and lymph node metastasis. The OK-432 it group with positive TILs showed a significant decrease in metastatic lymph node frequency and in the number of lymph node micro- metastatic foci when compared to the control group. This study showed that only one time preoperative OK-432 it, particularly when it triggers TILs, is effective for reduction of regional lymph node metastasis. OK-432 it probably acts partly by eliminating micro-metastatic foci in lymph nodes. Preoperative intratumoral injection of OK-432 is technically very easy and has no serious adverse effects, so it is a promising form of neoadjuvant immunotherapy for advanced gastric cancer.

Pseudo-spikes are common in histologically benign lymphoid tissues

T cell receptor gene rearrangement is a classic marker of T cell clonality and is a useful adjunct in the diagnosis of T cell lymphomas and leukemias. Rearranged V-J gene segments amplified by polymerase chain reaction (PCR) are traditionally analyzed by polyacrylamide gel electrophoresis. We and others have analyzed TCR-gamma PCR products using capillary gel electrophoresis, which produces single nucleotide resolution and provides improved diagnostic sensitivity over conventional methods. However, with this marked increase in resolution and sensitivity, it is necessary to re-define normal variation of TCR-gamma gene rearrangement in control tissues to allow appropriate interpretation of monoclonality if present. Using DNA capillary gel electrophoresis, we examined the spectrum of normal patterns for TCR-gamma in a variety of T-cell-rich, histologically benign tissue types, including spleen, lymph node, tonsil, and blood, and compared this with the patterns in T cell lymphoma samples. We defined relative peak heights as h1/h2, where h1 represents the peak height of the largest peak above the normally distributed population, and h2 represents the peak height of the normally distributed curve. We found spikes in almost 20% of histologically benign samples with relative peak heights that were more than 0.5 and up to 1.5. We designated these as pseudo-spikes, because they may be mistaken for monoclonal spikes. In contrast, the relative peak height of the T cell lymphoma samples that showed clonal rearrangement was much higher than that of the pseudo-spikes, being at least 2 in 11/11 and at least 3 in 10/11 cases. Our data suggest that peaks with relative height of at least 3 represent a true clonal population in diagnostic samples. Peaks with relative heights of less than 1.5 may be insignificant, while peaks with relative heights between 1.5 to 3 may warrant further evaluation. Although capillary gel electrophoresis is superior in assessing T cell clonality, caution must be exercised when interpreting results, because pseudo-spikes appear to be common in benign tissues with lymphoid populations and are not necessarily indicative of clonal malignant T cell population.

Identification of Natural Antigenic Peptides of a Human Gastric Signet Ring Cell Carcinoma Recognized by HLA-A31-Restricted Cytotoxic T Lymphocytes

Peptides of human melanomas recognized by CD8+ CTLs have been identified, but the nature of those of nonmelanoma tumors remains to be elucidated. Previously, we established a gastric signet ring cell carcinoma HST-2 and HLA-A31 (A*31012)-restricted autologous CTL clone, TcHST-2. In the present study, we determined the natural antigenic peptides of HST-2 cells. The purified preparation of acid-extracted Ags was submitted to the peptide sequencer, and one peptide, designated F4.2 (Tyr-Ser-Trp-Met-Asp-Ile-Ser-Cys-Trp-Ile), appeared to be immunogenic. To confirm the antigenicity of F4.2 further, we constructed an expression minigene vector (pF4.2ss) coding adenovirus E3, a 19-kDa protein signal sequence plus F4.2. An introduction of pF4.2ss minigene to HST-2 and HLA-A31(+) allogeneic tumor cells clearly enhanced and induced the TcHST-2 reactivity, respectively. Furthermore, when synthetic peptides of F4.2 C-terminal-deleted peptides were pulsed to HST-2 cells, F4.2-9 (nonamers), but not F4.2-8 or F4.2-7 (octamer or heptamer, respectively), enhanced the reactivity of TcHST-2, suggesting that the N-terminal ninth Trp might be a T cell epitope. This was confirmed by lack of antigenicity when using synthetic substituted peptides as well as minigenes coding F4.2 variant peptides with Ala or Arg at the ninth position of F4.2. Meanwhile, it was indicated that the sixth position Ile was critically important for the binding to HLA-A31 molecules. Thus, our data indicate that F4.2 may work as an HLA-A31-restricted natural antigenic peptide recognized by CTLs.

A novel negative regulator molecule, Cho-1, is involved in the cytotoxicity by human natural killer cells but not in cytotoxic T lymphocytes

We previously reported the cytotoxic negative regulatory molecule, Cho-1, that was expressed on the cell surface of rat fetal fibroblast cells in the cytotoxicity by natural killer (NK) cells. This molecule was IFN-gamma-inducible, but appeared to be different from MHC class I. It was expressed on NK-resistant cells but not on NK-sensitive murine target cells such as YAC-1. In this paper, first we determined whether Cho-1 could also act as the negative regulatory molecule in a human NK-resistant HEPM line. Our data strongly suggested that Cho-1 could act as such a negative regulatory molecule in human NK cytotoxicity. The immunoprecipitates made with HEPM cell lysate and anti-MHC class I monoclonal antibody (mAb) did not react against anti-Cho-1 mAb, indicating that Cho-I was different from MHC class I. Second, an assessment was made as to whether or not this molecule is involved in the cytotoxicity of CD8 (+) cytotoxic T lymphocytes (CTL) against human autologous tumor cells. The data indicated that although this cell surface molecule was expressed on certain tumor lines, it was not involved in the cytotoxic mechanism of CTL. Thus, Cho-1 appeared to be the novel regulatory molecule in the NK cytotoxic mechanism.

Cytotoxicity of histocompatibility leukocyte antigen-DR8-restricted CD4 killer T cells against human autologous squamous cell carcinoma

Although CD8+ killer T cells reacting against human autologous tumor cells have recently been studied in detail, little is known about the cytotoxic mechanism of CD4+ T cells against such tumor cells. In order to investigate this, we have established CD4+ cytotoxic T lymphocyte TcOSC-20 lines. TcOSC-20 showed selective cytotoxic activity against autologous OSC-20 cells, derived from a cancer of the tongue, in an HLA-DR-restricted fashion. HLA-DR8 (DRB1*08032) is the only DR molecule expressed on OSC-20 cells, and anti-DR8 monoclonal antibody could inhibit the cytotoxicity, suggesting that HLA-DRB1*08032 is the tumor rejection antigen-presenting molecule to TcOSC-20. The Fas ligand was expressed on TcOSC-20 lines, and its expression was induced upon mixed lymphocyte-tumor cell culture of autologous peripheral blood lymphocytes. Furthermore, the cytotoxicity of TcOSC-20 was inhibited by anti-Fas ligand antibody. These data imply that TcOSC-20 lines recognize the tumor antigenic peptide presented by HLA-DR8, and exert cytotoxicity against autologous tumor cells via a Fas-mediated cytotoxic pathway.