immune complex

(noun)

An immune complex is formed from the integral binding of an antibody to a soluble antigen. The bound antigen acting as a specific epitope, bound to an antibody is referred to as a singular immune complex.

Related Terms

Examples of immune complex in the following topics:

  • Immune Complex Autoimmune Reactions

    • An immune complex is formed from the integral binding of an antibody to a soluble antigen and can function as an epitope.
    • An immune complex is formed from the integral binding of an antibody to a soluble antigen.
    • The bound antigen acting as a specific epitope, bound to an antibody is referred to as a singular immune complex .
    • Type III hypersensitivity reactions are immune complex-mediated.
    • An immune complex is formed from the integral binding of an antibody to a soluble antigen.

  • Type III (Immune Complex) Reactions

    • When these antigens bind antibodies, immune complexes of different sizes form.
    • Large complexes can be cleared by macrophages but macrophages have difficulty in the disposal of small immune complexes.
    • These immune complexes insert themselves into small blood vessels, joints, and glomeruli, causing symptoms.
    • Often, immunofluorescence microscopy can be used to visualize the immune complexes.
    • An immune complex is formed from the integral binding of an antibody to a soluble antigen.

  • Hypersensitivity

    • A hypersensitivity reaction refers to an overreactive immune system triggered by allergies and autoimmunity.
    • Hypersensitivity reactions require a pre-sensitized (immune) state of the host .
    • Cytotoxic Hypersensitivity (Type II) is an immune response to human cells with foreign antigens.
    • Immune Complex Hypersensitivity (Type III) is an immune response to immune complexes (antigen-antibody complexes) that become deposited in a given area.
    • This results in continuous localized immune attack (and ensuing tissue damage).

  • Immunoassays for Disease

    • Immunology is the study of molecules, cells, and organs that make up the immune system.
    • When a foreign agent penetrates the first line of resistance, an immune reaction is elicited and immune cells are recruited into the site of infection to clear microorganisms and damaged cells by phagocytosis.
    • If the inflammation remains aggravated, antibody-mediated immune reaction is activated and different types of immune cells are engaged to resolve the disease.
    • The immune system is composed of cellular and humoral elements.
    • Most assays rely on the formation of large immune complexes when an antibody binds to a specific antigen which can be detected in solution or in gels.

  • Types of Adaptive Immunity

    • The adaptive immune response is mediated by B and T cells and creates immunity memory.
    • The adaptive immune system mounts a stronger, and antigen specific immune response after the innate immune response fails to prevent a pathogen from causing an infection.
    • There are two subdivisions of the adaptive immune system: cell-mediated immunity, and humoral immunity.
    • Antibodies to provide a number of functions in humoral immunity.
    • Their other main function is complement pathway activation, in which circulating proteins are combined in a complex cascade that forms a membrane attack complex on a pathogen cell membrane, which lyses the cell.

  • Overview of Adaptive Immunity

    • The adaptive immune system works to protect and heal the body when the innate immune system fails.
    • The adaptive immune system starts to work after the innate immune system is activated.
    • The adaptive immune response occurs a few days after the innate immune response occurs.
    • Adaptive immunity is triggered when a pathogen evades the innate immune system for long enough to generate a threshold level of an antigen.
    • In most cases, T cells only recognize an antigen if it is carried on the surface of a cell by one of the body's own MHC, or major histocompatibility complex, molecules.

  • Type IV (Delayed Cell-Mediated) Reactions

    • Cell-mediated immunity is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
    • Historically, the immune system was separated into two branches: humoral immunity, for which the protective function of immunization could be found in the humor (cell-free bodily fluid or serum) and cellular immunity, for which the protective function of immunization was associated with cells.
    • Therefore in cell mediated immunity cytokines are not always present.
    • 3. stimulating cells to secrete a variety of cytokines that influence the function of other cells involved in adaptive immune responses and innate immune responses
    • CD4+ helper T cells recognize antigen in a complex with Class 2 major histocompatibility complex.

  • Immunological Memory

    • During the adaptive immune response to a pathogen that has not been encountered before, known as the primary immune response, plasma cells secreting antibodies and differentiated T cells increase, then plateau over time.
    • This is known as the secondary immune response.
    • The result is a more rapid production of immune defenses.
    • The immune response to vaccination may not be perceived by the host as illness, but still confers immune memory.
    • A helper T cell recognizes the MHC II–antigen complex and activates the B cell.

  • Antigen-presenting Cells: B and T cells

    • The adaptive immune response activates when the innate immune response insufficiently controls an infection.
    • The two types of lymphocytes of the adaptive immune response are B and T cells .
    • Instead, they recognize antigens presented on major histocompatibility complexes (MHCs) that cells use to display which proteins are inside of them.
    • B cells are involved in the humoral immune response, which targets pathogens loose in blood and lymph, while T cells are involved in the cell-mediated immune response, which targets infected cells.
    • Explain the role played by B and T cells in the adaptive immune system

  • The Complement System

    • The serum complement system, which represents a chief component of innate immunity, not only participates in inflammation but also acts to enhance the adaptive immune response.
    • More recently, however, the role of the complement in the immune response has been expanded due to observations that link complement activation to adaptive immune responses.
    • Initiation of the classical pathway occurs when C1q, in complex with C1r and C1s serine proteases (the C1 complex), binds to the Fc region of complement-fixing antibodies (generally IgG1and IgM) attached to pathogenic surfaces.
    • The larger fragments associate to form C4bC2a on pathogenic surfaces, and the complex gains the ability to cleave C3 and is termed the C3 convertase.
    • It has become increasingly understood that complement functions in host defense extend beyond innate immune responses.