What are the immunologically active components of Bacille Calmette-Guérin in therapy of superficial bladder cancer?

Abstract

The subcomponents of bacille Calmette‐Guérin (BCG) involved in the mechanism of action of intravesical BCG immunotherapy used for prophylaxis of superficial bladder cancer recurrences have been poorly investigated. We purified various BCG subcomponents and analyzed in vitro their ability to enhance a Th1 polarized immune response as well as to increase lymphocyte‐mediated cytotoxicity against bladder tumors. Human peripheral blood mononuclear cells (PBMCs) from healthy purified protein derivative–positive subjects were incubated for 7 days with whole BCG and various fractions (BCG cell wall, plasma membrane, cytosol, purified polysaccharides as glucan or arabinomannan, purified native proteins from BCG culture filtrate, recombinant 22 kDa protein, phosphate transporter PstS‐2 and ‐3 proteins). IFN‐γ, IL‐12, IL‐2, and IL‐6 production by stimulated PBMCs was compared to unstimulated controls and the phenotype of expanded cells analyzed by flow cytometry (FACS analysis). A 51Cr‐release assay monitored the cytotoxicity of amplified effector cells against T24 bladder tumor cells. Live BCG and most of its subcomponents (with the exception of cytosol, PstS‐2 and ‐3) significantly enhanced IFN‐γ and IL‐12 secretion, expanded CD3–CD56+ cells and the non‐MHC‐restricted cytotoxicity against bladder tumor cells compared to unstimulated controls (all P < 0.001, t‐test). IL‐2 receptor blockage resulted in a clear reduction in the cytotoxic activity of stimulated PBMCs. Numerous BCG subcomponents thus provide positive stimuli for Th1 cell differentiation and enhance in vitro, non‐MHC‐restricted cytotoxicity against bladder tumor cells. Our findings provide the basis for the therapeutic use of several of these subfractions in experimental animal models bearing bladder tumors. Int. J. Cancer 87:844–852, 2000. © 2000 Wiley‐Liss, Inc.

Revisiting the Structure of the Anti-neoplastic Glucans of Mycobacterium bovis Bacille Calmette-Guérin

“…13 MHz for 1 H and at 125.77 MHz for 13 C using a 5-mm BBI probe. The temperature was maintained at 343 K to obtain a reasonable line width.…”

“…The parameters for the two-dimensional heteronuclear ( 1 H-13 C) multiple quantum correlation (HMQC) spectra were as follows: inv4gptp standard Bruker® program, 1.5-s recycle delay, 0.68-s acquisition time, GARP 13 C decoupling during acquisition. 13 C-NMR spectra were obtained using the Bruker® DEPT (distortionless enhancement by polarization transfer) sequence.…”

“…These polysaccharides are also produced by tubercle bacilli inside macrophages (11) and are involved in the nonopsonic binding of M. tuberculosis to mammalian cells through the complement receptor 3 (12). More importantly, polysaccharides with similar chromatographic behavior were purified from the Pasteur substrain of BCG and were shown to exhibit an anti-tumor activity against superficial bladder cancer (13). Finally, glycogen-like ␣-glucans have been character-ized from the cell wall preparations of an unspecified substrain of M. bovis BCG (14).…”

Mechanism responsible for the antitumor effect of BCG-CWS using the LEEL method in a mouse bladder cancer model

“…As a result, BCG components should be used for clarifying the machinery associated with BCG therapy. Although an immune response against BCG components in vitro using peripheral blood mononuclear cells has been demonstrated [11], a definitive understanding of the mechanism of BCG therapy is not available. The reason for this is that it is currently not possible to deliver the main immune active component of BCG to cells in an efficient manner.…”

Preclinical evaluation of superantigen (staphylococcal enterotoxin B) in the intravesical immunotherapy of superficial bladder cancer

“…However, cytotoxic activity of activated T lymphocytes within a complex local immune response against bladder cancer cells and secretion of several cytokines involved in the local immune response were demonstrated in in vitro cultures and in the urothelium of BCG-treated patients. [3][4][5][6] Other extremely potent activators of T lymphocytes are superantigens. Superantigens are proteins or peptide factors produced by various microorganisms like bacteria, mycoplasma or viruses.…”