immunoglobulin G

Examples of immunoglobulin G in the following topics:

• Complement Fixation

  • The first component is an indicator system that uses combination of sheep red blood cells, complement-fixing antibody such as immunoglobulin G produced against the sheep red blood cells and an exogenous source of complement usually guinea pig serum.

• Serology

  • Immunoglobulin M (IgM) is an antibody produced during the primary immune response and plays a significant role fighting infection.
  • Meanwhile, the B cells are producing highly specific Immunoglobulin G (IgG) more slowly.
  • Once IgG is produced in quantity, the IgG plays a greater role in the removal of antigens from the body due to its ability to bind to the antigen molecules more tightly.
  • This is followed by a decrease of IgM as the amount of IgG increases.
  • Medical laboratory personnel can identify the course and duration of an infection by measuring the ratio of IgM to IgG in the bloodstream.

• Primary Immunodeficiency Diseases

  • Tthe three most important types of antibodies are IgG, IgA and IgM.
  • Quantification of the different types of mononuclear cells in the blood (lymphocytes and monocytes): different groups of T lymphocytes (dependent on their cell surface markers, e.g.
  • Tests for B cell function: antibodies to routine immunizations and commonly acquired infections, quantification of IgG subclasses
  • In primary antibody deficiencies, one or more isotypes of immunoglobulin are decreased or don't function properly.
  • This may range from immunoglobulin replacement therapy in antibody deficiencies—in the form of intravenous immunoglobulin (IVIG) or subcutaneous immunoglobulin (SCIG)—to hematopoietic stem cell transplantation for SCID and other severe immunodeficiences.

• Antibody Structure

  • Antibodies can be divided into five classes (IgM, IgG, IgA, IgD, and IgE) based on their physiochemical, structural, and immunological properties.
  • Ig stands for immunoglobulin, another term for an antibody.
  • The properties of immunoglobulins and their basic structures are shown in the table .
  • The total number of IgA molecules in these bodily secretions is greater than the number of IgG molecules in the blood serum.
  • Immunoglobulins (antibody classes) have different functions, but all are composed of light and heavy chains that form a Y-shaped structure.

• Antibodies: Classes and Affinity Maturation

  • Isotype or class switching is a biological process occurring after activation of the B cell, allowing the cell to produce different classes of antibodies (IgA, IgE, or IgG) .
  • The different classes of antibody (and thus effector functions) are defined by the constant (C) regions of the immunoglobulin heavy chain.
  • After activation, accordingly, an antibody with a IgG, IgA, or IgE effector function might be summoned to effectively eliminate an antigen.
  • This process results in an immunoglobulin gene that encodes an antibody of a different isotype.
  • Intravenous immunoglobulin, if not otherwise noted, consists of polyvalent IgG.

• Isotype Class Switching

  • In placental mammals there are five antibody isotypes: IgA, IgD, IgE, IgG and IgM.
  • They are each named with an "Ig" prefix that stands for immunoglobulin (another name for antibody) and differ in their biological properties, functional locations, and ability to deal with different antigens.
  • B cells begin to express both IgM and IgD when they reach maturity; the co-expression of both of these immunoglobulin isotypes renders the B cell 'mature' and ready to respond to an antigen.
  • Immunoglobulin class switching (or isotype switching, or isotypic commutation, or class switch recombination (CSR)) is a biological mechanism that changes a B cell's production of antibody from one class to another; for example, from an isotype called IgM to an isotype called IgG.
  • This allows different daughter cells from the same activated B cell to produce antibodies of different isotypes or subtypes (e.g.

• The Complement System

  • n the classical pathway, C1 binds with its C1q subunits to Fc fragments (made of CH2 region) of IgG or IgM, which forms a complex with antigens.
  • C4b and C3b are also able to bind to antigen-associated IgG or IgM, to its Fc portion.
  • Such immunoglobulin-mediated binding of the complement may be interpreted, as that the complement uses the ability of the immunoglobulin to detect and bind to non-self antigens as its guiding stick.

• Adaptive Immunity and the Immunoglobulin Superfamily

  • Adaptive immunity is stimulated by exposure to infectious agents and recruits elements of the immunoglobulin superfamily.
  • Immunoglobulins are produced in a membrane-bound form by B lymphocytes.
  • These antibodies are part of a larger family called the immunoglobulin superfamily.
  • They all possess a domain known as an immunoglobulin domain or fold.
  • Describe the role of immunoglobulins in the adaptive immune response, specifically in humoral immunity

• Structure and Function of Antibodies

  • An antibody (formally called immunoglobulin) is a large Y-shaped glycoprotein produced by B-cells and used by the immune system to identify and neutralize pathogens.
  • Antibodies are glycoproteins belonging to the immunoglobulin superfamily, and are typically made of basic structural units—each with two large heavy chains and two small light chains.
  • IgG: Has four different forms,  and provides the majority of antibody-based immunity against invading pathogens, because it is the best opsonin of any type of antibody.
  • Eliminates pathogens in the early stages of B cell mediated (humoral) immunity before there is sufficient IgG.
  • Like IgG, it can also activate the classical complement system.

• Cytotoxic Autoimmune Reactions

  • Three main sets of genes are suspected in many autoimmune diseases: immunoglobulins, T-cell receptors and the major histocompatibility complexes (MHC).
  • Immunoglobulins and the T-cell receptors are involved in the recognition of antigens and they are inherently variable and susceptible to recombination.
  • McDevitt, G.