Nonspecific immunostimulation against viruses

Anticancer activity of mycobacterial DNA: effect of formulation as chitosan nanoparticles

Mycobacterium phlei (M. phlei) DNA inhibits cancer cell division but is susceptible to degradation by DNase. Chitosan forms nanoparticulate polyelectrolyte complexes with DNA, and may thus reduce nuclease degradation. We have characterized chitosan-DNA nanoparticle formation, determined DNase susceptibility, and evaluated their antiproliferative activity. Nanoparticle diameter initially decreased with increasing phosphate charge density. However nanoparticle diameter increased above 6 micromol of phosphate. Particle aggregation occurred at 16.2 micromol phosphate and was related to reduced surface charge. Incorporation of DNA within chitosan nanoparticles significantly decreased degradation by DNase. The ability of M. phlei DNA-chitosan nanoparticles to inhibit melanoma cell division was determined relative to M. phlei DNA and a cationic liposomal M. phlei DNA formulation. M. phlei DNA had antiproliferative activity (MTT reduction, IC50 = 0.9 mg/ml) without intrinsic cytotoxicity (LDH release, ED50 > 50 microg/ml). Cationic polyphosphate chitosan nanoparticles were inert (antiproliferative IC50 > 1 mg/ml, ED50 > 1 mg/ml). M. phlei DNA-chitosan nanoparticles were 20-fold more potent than M. phlei DNA. Cationic DOTAP/DOPE liposomes were cytostatic (IC50 = 49 microg/ml) and cytotoxic (ED50 = 87 microg/ml), and complexation of M. phlei DNA resulted in a significant reduction of antiproliferative activity. Chitosan nanoparticles may therefore be appropriate delivery vehicles for M. phlei DNA.

Mycobacterium phlei cell wall complex directly induces apoptosis in human bladder cancer cells

Intact mycobacteria and mycobacterial cell wall extracts have been shown to inhibit the growth of human and murine bladder cancer. Their mechanism of action is, however, poorly understood. Mycobacterium phlei mycobacterial cell complex (MCC) is a cell wall preparation that has mycobacterial DNA in the form of short oligonucleotides complexed on the cell wall surface. In this study, we have investigated the possibility that MCC has anti-cancer activity that is mediated by two different mechanisms--a direct effect on cancer cell proliferation and viability and an indirect effect mediated by the production of interleukin 12 (IL-12), a cytokine known to possess anti-cancer activity. We have found that, although MCC is a potent inducer of IL-12 and IL-6 synthesis in monocytes and macrophages either in vitro or in vivo, it is unable to induce the synthesis of either IL-12, IL-6 or granulocyte-macrophage colony-stimulating factor (GM-CSF) by the human transitional bladder cancer cell lines HT-1197 and HT-1376. MCC is not directly cytotoxic towards these cancer cells, but induces apoptosis as determined by nuclear DNA fragmentation and by the release of nuclear mitotic apparatus protein. Mycobacterium phlei DNA associated with MCC is responsible for the induction of apoptosis. Our results indicate that MCC directly effects bladder cancer cells by inhibiting cellular proliferation through the induction of apoptosis, and has the potential for an indirect anti-cancer activity by stimulating cancer-infiltrating monocytes/macrophages to synthesize IL-12.

Effect of Mycobacterium phlei on the development of immunity to Babesia bigemina

The immunomodulatory role of Mycobacterium phlei against intracellular blood protozoan Babesia bigemina was demonstrated following experimental immunisation and challenge in bovine calves. A lysate of erythrocytes infected (6 x 10(9)) with B. bigemina was used as a source of dead antigen either with Freund's complete adjuvant (FCA) or with a trypsinised culture of M. phlei as a non-specific immunomodulation (NSI) agent with appropriate controls. Following virulent challenge with B. bigemina infected erythrocytes (1 x 10(7)), the NSI printed calves showed 100% protection, while the dead antigen alone with FCA afforded 75% protection. The protective status of the immunising regimes was studied by clinicopathological parameters and assessment of humoral and cell-mediated immune responses. The role of babesial dead antigen and the effects of M. phlei on the development of immunity to B. bigemina is discussed.

Clinical results obtained in cattle and swine by means of biological immunostimulators

The conditioned infections due to opportunistic organisms, can be controlled by biological immunostimulators. The POLI-IF (Newcastle virus plus endotoxin of E. coli and Freund's incomplete adjuvant) rapidly induces the aspecific immunity. Given twice with 7-10 days interval in between, on occasion of a programmed stress (weaning, transport, crowding) it proved its efficacy in artificially suckled calves and in weaning piglets. The field trials, carried out on 2,782 treated calves in comparison with 2,909 untreated controls and on 4,387 piglets in comparison with 4,461 untreated controls, revealed statistically significant differences for P less than 0.005 among the groups of treated and control animals. The immunostimulator reduced the incidence of the disease, dead and discarded animals, as well as it shortened the mean duration of the disease in single heads. Though the way the POLI-IF acts is not perfectly known so far, yet it increases the serum bactericidal activity and the circulating leukocytes, while it induces high levels of IFN. In our opinion the activity of the POLI-IF is bound to 3 factors at least: activation of the complementary fractions, mobilization of the immunocompetent cells, induction of IFN.