tolerance

(noun)

The process by which the immune system does not attack an antigen

Related Terms

Examples of tolerance in the following topics:

  • Clonal Selection and Tolerance

    • The concept of central tolerance was proposed in 1959 as part of a general theory of immunity and tolerance.
    • It was hypothesized that it is the age of the lymphocyte that defines whether an antigen that is encountered will induce tolerance, with immature lymphocytes being tolerance sensitive.
    • Central tolerance is distinct from periphery tolerance in that it occurs while cells are still present in the primary lymphoid organs (thymus and bone-marrow), prior to export into the periphery.
    • Peripheral tolerance is generated after the cells reach the periphery.
    • Regulatory T cells can be considered both central tolerance and peripheral tolerance mechanisms, as they can be generated from self (or foreign)-reactive T cells in the thymus during T cell differentiation.

  • Biofilms, Persisters, and Antibiotic Tolerance

    • Biofilms and persisters are bacterial communities responsible for chronic diseases and antibiotic tolerance.
    • Persisters are multidrug tolerant cells present in all bacterial populations.
    • Persisters are not mutants, but rather phenotypic variants of the wild-type that upon inoculation produce a culture with similar levels of tolerance.
    • Biofilms and persisters are the cause of multidrug tolerance.
    • Explain the role of biofilms and persisters in multidrug tolerance, distinguishing this from multidrug resistance

  • Regulatory T Cells

    • The contribution of these populations to self-tolerance and immune homeostasis is less well defined.
    • An additional regulatory T cell subset, induced regulatory T cells, are also needed for tolerance and suppression.
    • Induced Regulatory T (iTreg) cells (CD4+CD25+Foxp3+) are suppressive cells involved in tolerance. iTreg cells have been shown to suppress T cell proliferation and experimental autoimmune diseases. iTreg cells develop from mature CD4+ conventional T cells outside of the thymus: a defining distinction between natural regulatory T (nTreg) cells and iTreg cells.
    • The contribution of nTreg cells versus iTreg cells in maintaining tolerance is unknown, but both are important.

  • Cell-Mediated Autoimmune Reactions

    • This reaction thereby overcomes the negative signals responsible for B cell self-tolerance without necessarily requiring loss of T cell self-tolerance.
    • Dendritic cells that are defective in apoptosis can lead to inappropriate systemic lymphocyte activation and consequent decline in self-tolerance.
    • DQ therefore is involved in recognizing common self-antigens and presenting those antigens to the immune system in order to develop tolerance from a very young age.
    • When tolerance to self proteins is lost, DQ may become involved in autoimmune disease.

  • Hyperthermophilic Archaea, H2, and Microbial Evolution

    • Some bacteria are even able to tolerate temperatures of around 100°C (212°F).
    • One extraordinary heat-tolerant hyperthermophile is the recently discovered Strain 121, an archaeon living at 121°C in the Pacific Ocean.

  • Environmental Diversity of Microbes

    • Their diversity also makes them tolerant of many other conditions, such as limited water availability, high salt content, and low oxygen levels.
    • They rely on specific physical and chemical factors such as measuring temperature, pH, and salinity within a certain geography to formulate a comparison among microbial communities and the environment different species can tolerate.

  • Acidobacteria

    • This is advantageous as the intracellular proteins are not required to develop tolerance against highly acidic conditions.

  • Non-Spore-Forming Firmicutes

    • These comprise a class of Firmicutes and are Gram-positive, low-GC, acid-tolerant, generally non-sporulating, non-respiring rod or cocci that are associated by their common metabolic and physiological characteristics.
    • The lactic acid bacteria (LAB) are rod-shaped bacilli or cocci , characterized by an increased tolerance to a lower pH range.
    • A Gram-positive, catalase-positive bacterium which is rod-shaped, and has the ability to form a tough, protective endospore, allowing the organism to tolerate extreme environmental conditions.

  • Microbial Environments and Microenvironments

    • For example, extremophilic species have been found that can tolerate the following environmental extremes:

  • Gas Requirements

    • Some example free-living diazotrophs include: 1) obligate anaerobes that cannot tolerate oxygen even if they are not fixing nitrogen.