Major histocompatibility complex class II antigen expression during potentiation of line-10 tumor immunity after intralesional administration of bacillus Calmette-Guérin

Canine transmissible venereal tumour: Cytogenetic origin, immunophenotype, and immunobiology. A review

Canine transmissible venereal tumour (CTVT) is the only known naturally occurring tumour that can be transplanted as an allograft across major histocompatibility (MHC) barriers within the same species, and even to other members of the canine family, such as foxes, coyotes and wolves. The progression of this tumour is unique in that, it follows a predictable growth pattern. In natural and experimental cases, the growth pattern includes progressive growth phase, static phase and regression phase, and this is followed by transplantation immunity in immunocompetent adults, while metastasis occurs in puppies and immunosuppressed dogs. Because of the uniqueness of CTVT transmission and progression, experimental investigations of various aspects of the biology of CTVT have been used to provide clues to the immunobiology of both animal and human tumours. This review examines the current state of knowledge of the aspects of the cytogenetic origin, immunophenotype, immunobiology and immunotherapy of CTVT.

Expression of ICAM-1 in implanted primary and metastatic squamous cell carcinomas in rats

FF6 tumor cells are derived from a spontaneous rat squamous cell carcinoma (SCC) which originally arose in the facial skin of a DA rat. In this study, FF6 tumor cells were implanted into rat oral mucosa to establish an ex vivo metastatic model. We analyzed the expression of intercellular cell adhesion molecule-1 (ICAM-1) in the implanted primary and metastatic FF6 tumors by immuno-staining with a monoclonal antibody (mAb) against ICAM-1. The implanted primary FF6 cells showed strong expression of ICAM-1, whereas the tumor cells of metastatic lesions showed weak or negative expression of ICAM-1. By immunostaining with mAb OX6, a number of MHC class II-positive macrophages were detected in tumor mesenchyme and surrounding the metastatic foci. These results suggested that the local immune reaction in the lymph node influenced the expression of ICAM-1 on tumor cells, and that MHC class II-positive macrophages may play a role in transplanted tumor growth and metastases.

Immunotherapy of a plasmacytoma with attenuated salmonella

An attenuated strain of Salmonella typhimurium, SL3235, developed as a prototypic typhoid vaccine, is shown to retard growth of a murine plasmacytoma, TEPC-183, and to prolong survival of tumor-bearing mice. Live salmonella, but not acetone-killed organisms, had antitumor activity. The immunotherapeutic effect was demonstrable when the tumor was injected intralesionally or intraperitoneally. Increased survival, longer mean time to death, and retardation of tumor growth were found when the salmonella were given intralesionally as late as the sixth day post-tumor injection. Timing of salmonella inoculation, as well as the salmonella dose, had an effect on treatment efficacy. Injection of salmonella intraperitoneally exerted a strong antitumor effect when given as late as the third day post-tumor inoculation. The highest dose (2 x 10(6)) of salmonella was less effective than doses 10- or 100-fold lower. TEPC-183 plasmacytoma is rapidly growing and highly immunosuppressive, so the ability of the salmonella to exert therapeutic activity against it is a measure of the potency of the vaccine. These observations are of interest, as they show that a genetically engineered, avirulent strain of Salmonella has immunotherapeutic properties similar to those of BCG and other biological response modifiers, and might have clinical potential as an antitumor agent.

Specific tumor memory induced by polyethylene-glycol-modified interleukin-2 requires both helper and cytotoxic T cells

Local polyethylene-glycol (PEG)-modified interleukin-2 (IL-2) immunotherapy of the guinea pig Line 10 (L10) tumor was previously demonstrated to evoke long-lasting systemic immunity after cure of the tumor and metastases. T cells, most likely the helper T cell subpopulation, were demonstrated to be crucial to the antitumor effects. Here we show that systemic immunity is induced within 7 days after the start of PEG-IL-2 therapy, indicating a rapid systemic priming of L10-specific T cells. No in vitro cytotoxic activity was detected in cell suspensions obtained from the primary tumor site, the regional lymph node or the spleen when isolated during (days 21 and 28) intratumoral treatment with 200,000 IU PEG-IL-2. These data confirm our earlier results obtained with 60,000 IU PEG-IL-2. Moreover, no cytolytic activity was observed in the chromium-release assay after in vitro restimulation with irradiated tumor cells. Specific L10 immunity can be transferred using spleen cell suspensions. Depletion of such a suspension of helper T cells resulted in rejection of the primary tumor in two out of four animals, but all the guinea pigs developed lymph node metastases. Removal of the cytotoxic/suppressor phenotype caused rejection of the dermal tumor in four of eight guinea pigs, but the capacity to prevent lymph node metastases was retained in all animals. Thus, depletion of either subtype reduces, but does not abrogate, the capacity to transfer L10 immunity with spleen cells. In conclusion, our data suggest that tumor cell killing through direct T cell cytotoxicity is not the main mode of action in PEG-IL-2-induced L10 tumor regression. PEG-IL-2 therapy induces early systemic immunity, resulting in rejection of a distant tumor, and the transfer of this immunity depends mainly on the presence of helper T cells, although cytotoxic T cells may also play a role.

Polyethylene-glycol-modified interleukin-2 is superior to interleukin-2 in locoregional immunotherapy of established guinea-pig tumors

Polyethylene glycol-modified recombinant human interleukin-2 (PEG-IL-2) represents a cytokine with prolonged circulatory half-life and increased antitumor activity as compared to recombinant interleukin-2 (rIL-2) after systemic administration. We studied whether PEG-IL-2 would also be advantageous in locoregional immunotherapy using a syngeneic tumor model. Intradermal inoculation of line-10 tumor cells into the flanks of strain-2 guinea-pigs results in a fast-growing tumor and regional lymph-node metastases. Treatment schedules were started on day 7 after inoculation in animals with established tumors. First, groups of 5-6 animals were treated with repeated intratumoral and perilymphatic rIL-2 or PEG-IL-2 injections. PEG-IL-2 caused significant growth inhibition of both the primary tumor and the regional lymph-node metastases at lower doses and with less frequent administration than rIL-2. The best schedule for PEG-IL-2 was 3 injections a week for 5 weeks, resulting in cure of 4/17 and 5/5 (p less than 0.01) animals at the 2 most efficient dose levels tested. Subsequent experiments indicated that the intratumoral and not the perilymphatic injection route was essential for the obtained antitumor effect. Furthermore, 12/12 animals cured after PEG-IL-2 treatment rejected a rechallenge with line-10 tumor cells, whereas no cures were seen after rIL-2 injections. PEG-IL-2 therefore appears to be a valuable substance for intratumoral immunotherapy.

Major histocompatibility complex class II antigen expression on leucocyte subpopulations in the draining lymph node and tumour in the early phase of bacillus-Calmette-Guérin-induced tumour regression

We investigated the cellular composition and the major histocompatibility complex (MHC) class II antigen expression in the draining lymph node and the tumour during potentiation of the immune response by intralesional bacillus Calmette-Guérin (BCG) administration in the line 10 hepatocellular carcinoma in the strain 2 guinea-pig. Five days after its injection BCG induced a ninefold increase in the number of draining lymph node cells and an increased MHC class II expression. This increased MHC class II expression was mostly due to the selective increase of B cells in the lymph nodes, and to a lesser extent to the increase of T cells expressing MHC class II antigens. Taking into account this nine-fold increase, intralesional treatment of BCG increased considerably the number of T helper/inducer (anti-CT7) and T suppressor/cytotoxic (anti-CT6) lymph node cells expressing MHC class II antigen. The percentage of tumour-infiltrating T cells expressing MHC class II antigen in the tumour was higher than the percentage of T cells in the regional draining lymph node of non-treated guinea-pigs, indicating the presence of activated T cells in the tumour. After treatment with BCG no further increase in MHC class II expression was measured in the tumour, nor was any phenotypical change of the tumour-infiltrating T cells found. In conclusion, with the use of two-colour flow cytofluorometry we have shown that the potentiation of the already existing immune response to line 10 is accompanied by a considerable increase in T helper/inducer, T suppressor/cytotoxic cells and MHC class II antigen in the regional lymph node. Whether this is essential for the potentiation of the immune response causing tumour regression and long-lasting immunity is a subject for further study.