BCG immunopotentiation of an antitumor response: evidence for a cell-mediated mechanism

Maturation of human dendritic cells by cell wall skeleton of Mycobacterium bovis bacillus Calmette-Guérin: involvement of toll-like receptors

The constituents of mycobacteria are an effective immune adjuvant, as observed with complete Freund's adjuvant. In this study, we demonstrated that the cell wall skeleton of Mycobacterium bovis bacillus Calmette-Guérin (BCG-CWS), a purified noninfectious material consisting of peptidoglycan, arabinogalactan, and mycolic acids, induces maturation of human dendritic cells (DC). Surface expression of CD40, CD80, CD83, and CD86 was increased by BCG-CWS on human immature DC, and the effect was similar to those of interleukin-1beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), heat-killed BCG, and viable BCG. BCG-CWS induced the secretion of TNF-alpha, IL-6, and IL-12 p40. CD83 expression was increased by a soluble factor secreted from BCG-CWS-treated DC and was completely inhibited by monoclonal antibodies against TNF-alpha. BCG-CWS-treated DC stimulated extensive allogeneic mixed lymphocyte reactions. The level of TNF-alpha secreted through BCG-CWS was partially suppressed in murine macrophages with no Toll-like receptor 2 (TLR 2) or TLR4 and was completely lost in TLR2 and TLR4 double-deficient macrophages. These results suggest that the BCG-CWS induces TNF-alpha secretion from DC via TLR2 and TLR4 and that the secreted TNF-alpha induces the maturation of DC per se.

Inhibition of murine sarcoma cell adherence to polystyrene substrata by bacillus Calmette-Guérin: evidence for fibronectin-mediated direct antitumor activity of BCG

Bacillus Calmette-Guérin (BCG) inhibited adherence of S180 mouse sarcoma cells and WI38 human diploid fibroblasts to the polystyrene substratum of 24-well cluster dishes in a dose-dependent manner. This property was retained by washed or heat-killed bacilli, but not by the vaccine filtrate or by the spent bacterial culture medium. Adhesion of bacilli to nonadherent S180 cells was demonstrated by light and scanning electron microscopy, but was not seen after trypsinization of adherent cells, indicating that bacilli bind to cell-surface adhesins. Preincubation of bacilli with human fibronectin abolished their ability to inhibit S180 adherence, suggesting that the phenomenon may be mediated by interaction of bacilli with cell-surface fibronectin. Fibronectin pretreatment of the bacteria also decreased their inhibition of S180 tumor growth in vivo, indicating that this mechanism may be at least partly responsible for BCG vaccine's observed antineoplastic activity.

High-dose inhibition and low-dose enhancement of murine sarcoma growth exhibited by BCG vaccine

An in vivo assay for BCG anti-cancer efficacy was developed, utilizing subcutaneous injection into CFW Swiss-Webster mice of cultured S180 sarcoma cells and mixed with freeze-dried TiceTM BCG vaccine. A BCG dose of 0.156-1.56 mg dry weight significantly inhibited tumor formation, but a BCG dose of 0.156-1.56 micrograms significantly enhanced tumor growth, evidenced by increased tumor incidence, volume and initial growth rate. These antagonistic activities may contribute to the high variability of BCG anti-cancer efficacy seen in animals and humans and indicate the need to exercise caution when employing even low doses of BCG for cancer immunotherapy.

Tumor bearer T cells suppress Bacillus Calmette-Guérin-potentiated antitumor responses. III. Identification of an auxiliary efferent suppressor-T-cell population

T cells (Ts-eff) induced in BALB/c mice by subcutaneous (sc) growth of syngeneic Meth A tumors can adoptively suppress the effector phase of delayed-type hypersensitivity (DTH) in Bacillus Calmette-Guérin (BCG)-primed and unprimed recipients which have been sensitized with irradiated Meth A cells but they do not inhibit the augmented DTH response in recipients inoculated with cyclophosphamide (CY) 2 days prior to sensitization. By reconstituting CY-treated immunized recipients with selected spleen cell populations, it has been demonstrated that Ts-eff suppress DTH by interacting with a second or auxiliary suppressor cell population present in immune but not normal spleens. These auxiliary suppressor cells (Ts-aux) are Thy+, Lyt 1-2+ and I-J+, phenotypically similar to Ts-eff. Their activity is not influenced by B-cell depletion. Unlike Ts-eff, Ts-aux do not bear receptors specific for Meth A cells. Ts-aux and Ts-eff share similar sensitivity to irradiation and high dose (100 mg/kg) CY but unlike Ts-eff, Ts-aux are cortisone sensitive, nondividing, nonadherent cells which are absent from the thymus. The phenotype and mechanism of action of Ts-aux resemble those of the auxiliary or Ts3 cells defined in models of contact sensitivity, DTH to simple haptens, and in vitro antibody responses.

Tumor-host cell interactions in rats bearing Shay chloroma--ultrastructural observations in animals receiving specific and nonspecific cancer immunotherapy

Tumors of the rats bearing Shay chloroma treated with specific (polymerised tumor particles) and nonspecific (PPD tuberculin) cancer immunotherapy were assessed on electron microscopy with special emphasis on the interactions between the host's effector cells and the tumor targets. Attempt was made to cast light on the differences previously found in the effects of these two immunotherapy models on this particular tumor. Lymphocytes were found apposited to the tumor cells in all animals, but the nature of this contact varied from intimate in series B and C (animals receiving PPD) to extremely loose in series A (specific mode of therapy instituted). The same was true with the cells of the MPS (mononuclear phagocyte system), which sometimes seemed to wrap the tumor cells by their slender cytoplasmic processes. A prominent hypertrophy and orientation of the Golgi complex of a small lymphocyte, recently shown to be characteristic of cytolytic T-cells in vitro, was visualized in one case of series C. The observations were interpreted to lend support to the idea that blocking activity due to the polymerised strong tumor antigens could be responsible for the adverse effects of the active specific cancer immunotherapy in this particular system.

Involvement of peritoneal macrophages in cellular responses to mastocytoma in resistant and susceptible mice

The involvement of peritoneal macrophages in rejection of mastocytoma cells in the C57BL/6 mice was examined in comparison to similar cell responses in susceptible DBA/2 mice. By means of scanning and transmission electron microscopy it was found that macrophages constituted the major cell class responding to the mastocytoma cells in the peritoneum of both mouse strains. However, in the resistant mouse strain macrophages formed the predominant cell type during the course of tumor growth. Furthermore, tissue culture of peritoneal exudate cells from this resistant mouse strain injected with mastocytoma cells five days earlier failed to grow out tumor cells. On the other hand, macrophages decreased in number in the susceptible DBA/2 mouse strain and tumor cells did grow readily in vitro when peritoneal cells containing tumor cells and macrophages were cultured in vitro. These results indicate that macrophages constitute an important cell class in resistance of a mouse strain which is now susceptible to mastocytoma cells. The ultrastructural study provided some insight into the nature of the cell types involved and their interaction with the tumor cell.

Adjuvant immunotherapy with BCG in squamous-cell bronchial carcinoma. Immune-reactivity in relation to immunostimulation (preliminary results in a controlled trial)

Jansen, H M, The, T H, de Gast, G C, Esselink, M T, van der Wal, A M, and Orie, N G M (1978).Thorax, 33, 429-438. Adjuvant immunotherapy with BCG in squamous-cell bronchial carcinoma. Immune-reactivity in relation to immunostimulation (preliminary results in a controlled trial). Twenty-nine patients with, at operation, evidence of locally advanced primary squamous-cell bronchial carcinoma (stage II, UICC, Geneva, 1974) had lung resection to remove all the visible tumour. Postoperatively a randomly chosen group of 16 patients received adjuvant BCG immunostimulation by scarifications, while the control group received no adjuvant treatment. Follow-up studies were done from three to 23 months. Immune-reactivity in vivo with PPD and DNCB skin tests, and in vitro with E-rosetting tests and lymphocyte transformation tests with PHA, Con A, diphtheria toxoid, and PPD was monitored in 10 treated and in seven untreated patients. Recurrence rates decreased appreciably in the BCG-stimulated group after a six to 23 months' follow-up (p<0·005). A pronounced increase in both in-vivo and in-vitro immune-reactivity went in parallel with a more favourable clinical outcome in the BCG-treated group. In these cases there was a significant increase in skin reactivity to PPD three months after surgery (p<0·025) and a statistically significant rise in lymphocyte reactivity to Con A (p<0·05), diphtheria toxoid (p<0·01), and PPD (p<0·05) but not to PHA 12 months after surgery. DNCB skin reactivity increased as well in the BCG-treated group, but the number of individuals was too small for statistical evaluation. Increase in immune responsiveness did not occur in the control group and appeared to be independent of the initial immune state of the patients. No differences were found in the numbers of E-rosetting lymphocytes in relation to immunotherapy. It is concluded that adjuvant BCG immunotherapy used in patients with minimal residual bronchial carcinoma improves the prognosis and a favourable clinical outcome is mirrored by an increase in cellular immune reactivity.

Adjuvant effect of Bordetella pertussis vaccine to sheep erythrocytes in mice: enhancement of cell-mediated immunity by subcutaneous administration of adjuvant and antigen

The subcutaneous route (s.c.) was used to study the adjuvant effect of Bordetella pertussis vaccine (PV) on cell-mediated immunity to sheep erythorcytes (SRBC). The immune response was measured by a sensitive assay procedure in which the antigen is injected intracutaneously into the mouse ear and the inflammatory swelling is measured with calipers. PV significantly enhanced cell-mediated immunity to SRBC, and the enhancement persisted for at least 3 weeks. PV administered up to 6 days before SRBC also significantly enhanced the response; PV injected 1 or more days after SRBC was not effective. In addition, it was found that PV per se released into the suspension medium a cell-free component(s) (pertussis supernatant) that contributed significantly to adjuvanticity. The adjuvanticity of both PV and PS was completely eliminated by heat.

Vaccinia virus: the possibilities of its oncogenicity in humans

Contrary to the earlier generally accepted view that vaccinia virus replicates in the cytoplasm only of suitable target cells, steadily accumulating data show that the viral genome spends a limited period of time in the nucleus. This, together with the many cases where a close association has been suspected or established between skin cancer and vaccination, suggests that vaccinia virus may, under certain yet undefined physiological conditions, act as an oncogenic virus in humans.