DNA from Bacteria, but Not from Vertebrates, Induces Interferons, Activates Natural Killer Cells and Inhibits Tumor Growth

Abstract

The nucleic acid fraction from cells of 6 species of bacterium and 2 kinds of vertebrate, calf and salmon, was extracted and purified by the same procedures as described previously. When the spleen cells from BALB/c mice were incubated with the nucleic acid fraction from either of the bacteria, natural killer (NK) activity of the cells was remarkably elevated and the cells produced factors to activate macrophages and to inhibit viral growth. It was shown that the factor to activate macrophages was interferon (IFN)-gamma and that to inhibit viral growth was IFNalpha/beta. On the other hand, the nucleic acid fraction from either of the vertebrate cells did not show such activities. Pretreatment of the bacterial nucleic acid fraction with DNase, but not with RNase, abrogated completely the biological activities. The activities of the bacterial nucleic acid were not influenced by the presence of polymyxin B, an inhibitor of lipopolysaccharide (LPS), and the spleen cells from not only BALB/c mice but also LPS-insensitive C3H/HeJ mice were activated, indicating that the activities of the fraction were not ascribed to LPS contaminated possibly into the fraction, but to DNA itself. Intralesional injection with the bacterial DNA fraction caused regression of mouse IMC tumors, but the injection with the vertebrate DNA fraction did not. These findings prompted us to examine the biological activities of DNA samples from a variety of animals and plants, which were provided from other laboratories or purchased from manufacturers. All of the DNA samples from cells of 5 kinds of bacterium, 2 of virus and. 4 of invertebrate augmented NK activity and induced IFN, more or less, in mouse spleen calls, while the DNA from 10 kinds of vertebrate, including 3 of fish and 5 of mammal, showed no such activities. The DNA from 2 species of plants, were also inactive. Possible mechanisms to explain the different biological activities of DNA from different cell sources were discussed based on our previous finding that the particular palindromic sequences with a G-C motif (s) are required for induction of IFNs and activation of NK cells with synthetic 30-mer oligonucleotides.We have demonstrated that a DNA-rich fraction, extracted fromMycobacterium bovis BCG and designated MY-1 (22), exhibited strong antitumor activities against 98 3

CpG DNA and LPS induce distinct patterns of activation in human monocytes

“…15,18 Complete Freund's adjuvant consists of heat-killed dried Mycobacterium tuberculosis which includes mycobacterial DNA and components of the cell membrane including endotoxins. [22][23][24] Bacterial DNA has been known for its immunostimulatory activity for many years, 25,26 but the CpG-mediated mechanism responsible for this activity was unknown until recently. 5 Endotoxins in complete Freund's adjuvant contribute to its toxicity 27 which hamper its therapeutic use in humans in contrast to mice which are less sensitive to LPS.…”

Specificity and immunochemical properties of antibodies to bacterial DNA in sera of normal human subjects and patients with systemic lupus erythematosus (SLE)

“…As shown using synthetic oligonucleotides, immune activation by bacterial DNA results from sequences that consist of two 5 0 purines, an unmethylated CpG core and two 3 0 pyrimidines. These sequences are much more common in bacterial DNA than mammalian DNA, and suggest that bacterial DNA can function like endotoxin and trigger innate immunity during infection [3][4][5][6][7].…”

APC Stimulated by CpG Oligodeoxynucleotide Enhance Activation of MHC Class I-Restricted T Cells

“…(cytosine-phosphorothioate-guanine oligodeoxynucleotide (CpG ODN)) 4 can activate B cells, monocytes, and NK cells and induce production of a wide variety of cytokines (IL-6, IL-10, IL-12, IL-18, IFN-␣, IFN-␥, and TNF-␣) (1)(2)(3)(4)(5)(6)(7). CpG ODN can also function as potent immune adjuvants (8).…”