antibodies

Examples of antibodies in the following topics:

• Fluorescent Antibodies

  • Fluorescent antibodies are antibodies that have been tagged with a fluorescent compound to facilitate their detection in the laboratory.
  • The fluorescent antibody technique consists of labeling antibody with dyes such as fluorescein isothiocyanate (FITC).
  • The chemical manipulation in labeling antibodies with fluorescent dyes to permit detection by direct microscopy examination does not impair antibody activity.
  • Fluorescent antibody conjugates are commonly used in immunoassays.
  • In the direct technique, a fluorescent antibody is used to detect antigen-antibody reactions at a microscopic level.

• Neutralization Reaction

  • Neutralization reactions are used to inactivate viruses and evaluate neutralizing antibodies.
  • This usually involves the formation of a virus-antibody complex.
  • This virus-antibody complex can prevent viral infections in many ways.
  • Antibodies can also neutralize viral infectivity by binding to cell surface receptors.
  • Neutralizing antibodies have shown potential in the treatment of retroviral infections.

• Antibody Genes and Diversity

  • Complex genetic mechanisms evolved which allow vertebrate B cells to generate a diverse pool of antibodies from relatively few antibody genes.
  • Virtually all microbes can trigger an antibody response.
  • Several complex genetic mechanisms have evolved that allow vertebrate B cells to generate a diverse pool of antibodies from a relatively small number of antibody genes.
  • Some point mutations will result in the production of antibodies that have a lower affinity with their antigen than the original antibody, and some mutations will generate antibodies with a higher affinity.
  • Schematic diagram of an antibody and antigens.

• Antibody Structure

  • Variations in antibody structure allow great diversity of antigen recognition among different antibodies.
  • The constant domain, which does not bind to an antibody, is the same for all antibodies.
  • The large diversity of antibody structure translates into the large diversity of antigens that antibodies can bind and recognize.
  • Ig stands for immunoglobulin, another term for an antibody.
  • Prior to antibody secretion, plasma cells assemble IgM molecules into pentamers (five individual antibodies) linked by a joining (J) chain .

• Antibody Functions

  • Sometimes, antibodies can be transferred from one individual to another.
  • Phagocytic enhancement by antibodies is called opsonization.
  • In fact, antibodies exhibit different affinities (attraction) depending on the molecular complementarity between antigen and antibody molecules .
  • Typically, multimeric antibodies, such as pentameric IgM, are classified as having lower affinity than monomeric antibodies, but high avidity.
  • (b) An antibody may cross-react with different epitopes.

• Monoclonal Antibodies

  • Monoclonal antibodies are monospecific antibodies that recognize one specific epitope on a pathogen.
  • Monoclonal antibodies (mAb or moAb) are monospecific antibodies that are the same because they are made by identical immune cells that are all clones of a unique parent cell.
  • Monoclonal antibody therapy is the use of monoclonal antibodies (or mAb) to specifically bind to target cells or proteins.
  • This allows the transformation of murine antibodies in vitro into fully human antibodies.
  • Schematic diagram of an antibody and antigens.

• Agglutination Reactions

  • Agglutination is the visible expression of the aggregation of antigens and antibodies.
  • These conjugated particles are reacted with patient serum presumably containing antibodies.
  • Flocculation tests are designed for antibody detection and are based on the interaction of soluble antigens with antibodies, producing a precipitate of fine particles that can be seen with the naked eye.
  • It measures the antibody level produced by a host infected with that pathogen.
  • Red blood cells are used as carriers to detect antibodies from a patient's serum.

• Antibodies: Classes and Affinity Maturation

  • Virtually any microbe can trigger an antibody response.
  • Several complex genetic mechanisms have evolved allowing vertebrate B cells to generate a diverse pool of antibodies from a relatively small number of antibody genes.
  • One of these domains, the variable domain, is present in the heavy and light chain of every antibody, but is differentiated in antibodies generated from distinct B cells.
  • Combining these genes with an assortment of genes for other antibody domains generates a large cavalry of antibodies (i.e., a high degree of variability).
  • Some point mutations result in the production of antibodies having a weaker interaction (low affinity) with their antigen than the original antibody, and some generate antibodies with a stronger interaction (high affinity).

• Complement Fixation

  • Complement fixation is a method that demonstrates antibody presence in patient serum.
  • Complement fixation is a classic method for demonstrating the presence of antibody in patient serum.
  • If the serum contains antibody to the antigen, the resulting antigen-antibody complexes will bind all of the complement.
  • Sheep red blood cells and the anti-sheep antibody are then added.
  • If complement has not been bound by an antigen-antibody complex formed from the patient serum and known antigens, it is available to bind to the indicator system of sheep cells and anti-sheep antibody.

• Antibody Proteins and Antigen Binding

  • A region at the tip of the antibody protein is very variable, allowing millions of antibodies with different antigen-binding sites to exist.
  • Antibodies are heavy (~150 kDa) globular plasma proteins.
  • Heavy and light chains, variable and constant regions of an antibody
  • The general structure of all antibodies is very similar.
  • Heavy and light chains, variable and constant regions of an antibody