By: Karen Crawford, Ph.D.
President, List Biological Laboratories, Inc.
Many bacterial products are potent immune system activators, helping our bodies identify and defend against microbial invasions. The innate immune system or non-specific immune system is found in animals as well as in plants, fungi and insects and is employed when pathogens break through the outer barrier of skin, scales, or bark. It is important for any multicellular organism to be able to resist the bacterial pathogens, which can quickly infect tissues that are undefended. Lipopolysaccharides (List products #201 through #434) are frequently used in medical research to challenge the mammalian immune system and induce a cytokine response, setting off a chain of events in the body. Cytokines are released, attracting macrophages, which attack and “eat” the foreign bodies, and granulocytes, releasing histamines and toxins that are effective in killing bacteria. Lippolysaccharides have become an important tool in understanding how the body fights infections1 as well as for understanding inflammation. The chain of signaling set off by lipopolysaccharides includes G-protein activation2. LPS has been used to study neurological inflammation3, 4.
Other bacterial “antigens” make potent immune system activators and have slightly more specific effects. For example, challenge with cholera toxin B subunit (List Products #103B – #104) induces lymphoctes to produce a specific kind of T-cell5. Activation of the immune system can be quite different, depending on the specific bacteria and virulence factors. Somehow our bodies have learned to distinguish which bacteria are harmful and which are not; such as in the case of differential activation of immune cells (eosinophils) by probiotic bacteria compared to pathogens such as C. difficile6. Exotoxins from C. difficile are sold as List Products #152 to #155.
- Vassallo M, Mercié P, Cottalorda J, Ticchioni M, and Dellamonica P(2012) The role of lipopolysaccharide as a marker of immune activation in HIV-1 infected patients: a systematic literature review. Virology J. 9: 174. PMID: 22925532
- Sangphech N, Osborne BA, Palaga T (2014) Notch signaling regulates the phosphorylation of Akt and survival of lipopolysaccharide-activated macrophages via regulator of G protein signaling 19 (RGS19). Immunobiology 219(9):653-60. PMID: 24775271
- Kozlowski C and Weimer RM (2012) An Automated Method to Quantify Microglia Morphology and Application to Monitor Activation State Longitudinally In Vivo. PLoS One 7(2): e31814. PMID: 22457705
- Russo I, Amornphimoltham P, Weigert R, Barlati S, Bosetti F (2011) Cyclooxygenase-1 is involved in the inhibition of hippocampal neurogenesis after lipopolysaccharide-induced neuroinflammation. Cell Cycle 10(15):2568-73. PMID: 21694498
- Sun JB, Czerkinsky C, Holmgren J (2012) B lymphocytes treated in vitro with antigen coupled to cholera toxin B subunit induce antigen-specific Foxp3(+) regulatory T cells and protect against experimental autoimmune encephalomyelitis. J Immunology 188(4):1686-97. PMID: 22250081
- Hosoki K, Nakamura A, Nagao M, Hiraguchi Y, Tokuda R, Wada H, Nobori T, Fujisawa T (2010) Differential activation of eosinophils by “probiotic” Bifidobacterium bifidum and “pathogenic” Clostridium difficile. Int Arch Allergy Immunology 152 Suppl 1:83-9. PMID: 20523069