Self molecules

Examples of Self molecules in the following topics:

• Primary and Secondary Antibody Responses

  • Both innate and adaptive immunity depend on the ability of the immune system to distinguish between self and non-self molecules.
  • In immunology, self molecules are those components of an organism's body that can be distinguished from foreign substances by the immune system.
  • Conversely, non-self molecules are those recognized as foreign molecules.
  • One class of non-self molecules are called antigens (short for antibody generators) and are defined as substances that bind to specific immune receptors and elicit an immune response.

• Elements of Life

  • In such a reducing atmosphere, electrical activity can catalyze the creation of certain basic small molecules (monomers) of life, like amino acids.
  • A fundamental question is about the nature of the first self-replicating molecule.
  • The polymerization of nucleotides into random RNA molecules might have resulted in self-replicating ribozymes (RNA world hypothesis).
  • Using this apparatus, and using conditions thought to approximate the conditions on pre-biotic earth, they were able to catalyze the molecules of life like amino acids.

• Toll-Like Receptors

  • They are single, membrane-spanning, non-catalytic receptors that recognize structurally conserved molecules derived from microbes.
  • TLRs are a type of pattern recognition receptor (PRR) and recognize molecules that are broadly shared by pathogens but distinguishable from host molecules, collectively referred to as pathogen-associated molecular patterns (PAMPs).
  • Because of the specificity of Toll-like receptors (and other innate immune receptors) they cannot easily be changed in the course of evolution, these receptors recognize molecules that are constantly associated with threats (i.e., pathogen or cell stress) and are highly specific to these threats (i.e., cannot be mistaken for self molecules).
  • When activated, TLRs recruit adapter molecules within the cytoplasm of cells in order to propagate a signal.
  • Four adapter molecules are known to be involved in signaling.

• Clonal Selection and Tolerance

  • Central tolerance is the mechanism by which newly developing T cells and B cells are rendered non-reactive to self.
  • The theory that self-tolerance is 'learned' during lymphocyte development was a major conceptual contribution to immunology.
  • However, they exert their immune suppression in the periphery on other self (or foreign)-reactive T cells.
  • Positive selection ensures maturation of T cells whose receptors bind weakly to self major histocompatibility complex molecules.
  • "Self"-antigens from the body's own tissues 4.

• T Cell Receptors

  • T lymphocytes have a dual specificity: they recognize polymorphic residues of self major histocompatibility complex (MHC) molecules, which accounts for their MHC restriction; they also recognize residues of peptide antigens displayed by these MHC molecules, which is responsible for their specificity.
  • MHC molecules and peptides form complexes on the surface of antigen presenting cells (APCs).
  • T cells also express other membrane receptors that do not recognize antigens but participate in responses to antigens; these are collectively called 'accessory molecules'.
  • The physiologic role of some accessory molecules is to deliver signals to the T cells that function in concert with signals from the TCR complex to fully activate the cell.

• Immunoassays for Disease

  • Immunology is the study of molecules, cells, and organs that make up the immune system.
  • The function of the immune system is to recognize self antigens from non-self antigens and defend the body against non-self (foreign) agents.
  • Because antibodies can be produced against any type of macromolecule, antibody-based techniques are useful in identifying molecules in solution or in cells.
  • Recent methods employ pure antibodies or antigens that have been immobilized on a platform and that can be measured using an indicator molecule.

• Extracellular Immune Avoidance

  • These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance (EPS).
  • Another common strategy that is used is to mask antigens with host molecules in order to evade detection by the immune system.
  • With HIV, the envelope covering the viron is created from the host cell's outermost membrane making it difficult for the immune system to identify as a non-self structure.

• Cell-Mediated Autoimmune Reactions

  • A normal immune response is assumed to involve B and T cell responses to the same antigen, where B cells recognize conformations on the surface of a molecule for B cells, and T cells recognize pre-processed peptide fragments of proteins for T cells.
  • Together with the concept of T cell-B cell discordance, this idea forms the basis of the hypothesis of self-perpetuating autoreactive B cells.
  • This reaction thereby overcomes the negative signals responsible for B cell self-tolerance without necessarily requiring loss of T cell self-tolerance.
  • DQ isoforms can bind to and present foreign and self antigens to T-cells.
  • When tolerance to self proteins is lost, DQ may become involved in autoimmune disease.

• Cytotoxic Autoimmune Reactions

  • Autoimmunity is a result of the failure of an organism's immune system to recognize "self".
  • Autoimmunity is the failure of an organism in recognizing its own constituent parts as self, creating an immune response against its own cells and tissues.
  • The misconception that an individual's immune system is totally incapable of recognizing self antigens is not new.
  • These variations enable the immune system to respond to a very wide variety of invaders, but may also give rise to lymphocytes capable of self-reactivity.
  • Fewer correlations exist with MHC class I molecules.

• The Roles of Genetics and Gender in Autoimmune Disease

  • Autoimmunity is the failure of an organism in recognizing "self" which results in an immune response against its own cells and tissues.
  • Autoimmunity is the failure of an organism in recognizing its own constituent parts as self, which allows an immune response against its own cells and tissues.
  • The misconception that an individual's immune system is totally incapable of recognizing self antigens is not new.
  • These variations enable the immune system to respond to a very wide variety of invaders, but may also give rise to lymphocytes capable of self-reactivity.
  • Fewer correlations exist with MHC class I molecules.