Killer cells induced by stimulation with allogeneic tumor cells and subsequent culture with recombinant interleukin-2

Immunological characteristics of the effector cells induced by a combination therapy with cyclophosphamide and allogeneic lymphocytes

A significant inhibition of tumor growth was observed when sarcoma 180 (S180)-bearing ICR strain mice were treated by a combination therapy, with a low dose of cyclophosphamide (CY) and an inoculation of allogeneic lymphocytes collected from C57BL/6 mice. The growth-inhibitory effect was significantly increased by an inoculation of a relatively lower dose of allogeneic lymphocytes (1 x 10(5) cells) and CY. The effector cells induced in the mice treated with CY and allogeneic lymphocytes expressed the Lyt 1.2, Lyt 2.2, IL-2R antigens on their membrane surface and did not express the H2KbDb (donor H-2) antigen, and they showed a specific cytostatic activity against S180 cells. These results strongly suggested that a combination therapy with a low dose of CY with an inoculation of allogeneic lymphocytes augmented an induction of specific cytotoxic T lymphocytes in the tumor-bearing recipient mice.

Expression of the MAGE gene family in human head-and-neck squamous-cell carcinomas

The MAGE genes encode certain tumor-associated antigens recognized by cytotoxic T lymphocytes. We investigated the expression of the MAGE-1, -2, -3, -4, -41, and -6 genes in 88 head-and-neck squamous-cell carcinomas (83 fresh tumor samples and 5 cell lines), using a reverse-transcription-polymerase-chain-reaction assay, followed by dot-blot hybridization with sequence-specific oligonucleotides and/or restriction enzyme-pattern analysis. The MAGE-1, -2, -3, -4, -41 and -6 genes were expressed at the mRNA level in 27, 34, 36, 22, 16 and 35, respectively, of 83 fresh tumor samples. At least one of these genes was expressed in 59 of the 83 samples. Neither non-tumor inflammatory cells nor normal tissues were positive for these genes. The MAGE-1 gene was expressed relatively frequently in SCC of the oropharynx, hypopharynx and maxillary sinus, but at lower rates in SCC of the larynx and of the tongue and oral cavity. MAGE-1 was frequently expressed in poorly differentiated SCC, somewhat less frequently in moderately differentiated SCC, and only infrequently in well-differentiated SCC. The expression levels of the other MAGE genes also varied with the anatomic site as well as the degree of differentiation. Our results suggest that specific immunotherapy against MAGE gene products may be useful for patients with head-and-neck carcinomas.

The role of major histocompatibility complex expression on head and neck cancer cells in the induction of autologous cytotoxic T lymphocytes

Using head and neck tumors, we studied the role of HLA class I and DR antigens on tumor cells in cytotoxic T lymphocyte (CTL) induction. Expression of major histocompatibility complex (MHC) antigens was investigated by two-color flow cytometry analysis and for this study we used the tumor cells, over 50% of which expressed both HLA class I and DR antigens on their surface. In seven cases, tumor cells were divided into three groups according to the specificity of monoclonal antibodies (mAb) to MHC to study the role of MHC antigens on tumor cells in CTL induction: one was not blocked (MHC double-positive tumor), a second was blocked by anti-class I mAb (class-I-negative DR-positive tumor) and third was blocked by anti-DR mAb (class-I-positive DR-negative tumor). Subsequently, these tumors were used to stimulate an autologous mixed lymphocyte/tumor cell culture for 5 days (MLTC) followed by further cultivation with interleukin-2 for 12 days. The induced autologous tumor killer cells were most cytotoxic when non-treated tumors, which consist mainly of cells that are both HLA-class I and DR-positive, were used as stimulator cells. When the tumor cells blocked by anti-DR mAb were used as stimulators, autologous tumor killer activity was lower than that induced by tumor cells blocked by anti-class-I mAb. Moreover, cytolysis by autologous tumor killer cells induced by stimulation of non-treated tumor cells was blocked during the effector phase, 26.6%-42.3% and 32.7%-53.8% by anti-class-I and anti-DR mAb respectively, suggesting that majority of the autologous tumor killer cells are MHC-restricted CD8+ or CD4+ CTL. These results suggest that both MHC class I and class II antigens on head and neck tumor cells play a critical role in inducing CTL.

Establishment of a human cell line from maxillary squamous cell carcinoma and its biological features as a stimulator for induction of cytotoxic T lymphocytes

A cancer cell line named FS-1 was established from maxillary cancer of which histological diagnosis was well differentiated squamous cell carcinoma (SCC). The HLA class I typing showed that FS-1 expressed the same HLA class I antigens as those of the host lymphocytes. The chromosome analysis and nuclear DNA contents suggested that FS-1 was not a normal human cell. FS-1 is characteristic of SCC in that it grows adhesively on the surface of a culture flask. The structure of tumor tissue obtained from FS-1-transplanted nude mice is very much like the original tissue of SCC. The SCC-antigen was determined in the culture supernatant of FS-1. Autologous tumor killing activity was induced from peripheral blood lymphocytes of some patients suffering from head and neck SCC after mixed lymphocyte tumor culture with FS-1. Thus, FS-1 can serve as a useful allogeneic stimulator of SCC for induction of autologous tumor killing activity.

Induction of bacillus-Calmette-Guérin-activated killer cells from human peripheral blood mononuclear cells against human bladder carcinoma cell lines in vitro

Cytotoxicity against two human bladder carcinoma cell lines (BT-A and BT-B) was investigated using human peripheral blood mononuclear cells (PBMC) stimulated with viable bacillus Calmette-Guérin (BCG) or sonicated BCG (s-BCG). We applied a cytotoxicity assay based on radioactive labelling of tumour cells by incorporation of L[3H]methionine. The results were compared with the cytotoxicity exerted by lymphokine-activated killer (LAK) cells generated by interleukin-2 (IL-2) and interferon gamma (IFN gamma). BCG-stimulated PBMC showed a cytotoxic potential against BT-A and BT-B comparable to that of IFN gamma-generated LAK cells, but this did not reach the level of IL-2-generated LAK cells. We termed these cytotoxic effectors BCG-activated killer (BAK) cells. In contrast to their cytotoxicity against bladder tumour cells, BAK cells did not differ from unstimulated PBMC in the killing of K562 cells. Only viable but not sonicated BCG was able to induce cytotoxicity against BT-A and BT-B. We could demonstrate the presence of the cytokines IFN gamma, IL-2, tumour necrosis factor alpha (TNF alpha) and TNF beta in the supernatants harvested during the generation of BAK cells. Monoclonal antibodies neutralizing IFN gamma were able to inhibit BCG-mediated cytotoxicity, giving evidence of the involvement of IFN gamma in the induction of BAK cells. Furthermore, we performed experiments to investigate the cytotoxic potential of distinct cell populations. The cells effective in BCG-activated killing of bladder tumour cells could be localized within the CD8+/CD56+ lymphocyte subset. CD4+ cells and macrophages did not exhibit cytolytic activity. Our findings imply that the activation by BCG of CD8+/CD56+ killer cells might be an important antitumoral mechanism during BCG therapy against superficial urothelial bladder cancer.