secondary immune response

(noun)

The act of exposure to the same pathogen after the initial immune response. Memory B and T cells work to rapidly eliminate the pathogen to prevent reinfection.

Related Terms

Examples of secondary immune response in the following topics:

  • Immunological Memory

    • When B and T cells begin to replicate during an adaptive immune response, some offspring become long-lived memory cells.
    • These memory cells remember all specific pathogens encountered during the animal's lifetime and can thus call forth a stronger response, called the secondary immune response, if the pathogen ever invades the body again.
    • Following reinfection, the secondary immune response typically eliminates the pathogen before symptoms of an infection can occur.
    • During the secondary immune response, memory T cells rapidly proliferate into active helper and cytotoxic T cells specific to that antigen, while memory B cells rapidly produce antibodies to neutralize the pathogen.
    • Many parasitic pathogens, such as the plasmodium protist that causes malaria, haven't successfully been vaccinated against because it is challenging to develop a vaccine that is strong enough to stimulate an immune response (sufficient immunogenicity) without causing a live infection.

  • Specific T-Cell Roles

    • These cells can differentiate into one of several subtypes, including TH1, TH2, TH3, TH17, or TFH, which secrete different cytokines to facilitate a different type of immune response.
    • The secondary immune response mediated by memory T cells is much faster and more effective at eliminating pathogens compared to the initial immune response.
    • Effector memory cells may be either CD4+ or CD8+, and produce either helper or cytotoxic T cells in a secondary immune response.
    • Their major role is to shut down T cell-mediated immunity toward the end of an immune reaction and suppress auto-reactive T cells that escaped the process of negative selection in the thymus.
    • Natural killer T cells (NKT cells – not to be confused with natural killer cells) bridge the adaptive immune system with the innate immune system.

  • Maturation of B Cells

    • Immature B cells are produced in the bone marrow and migrate to secondary lymphoid tissues where some develop into mature B cells.
    • B cells are lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response, which is governed by T cells) .
    • B cells are an essential component of the adaptive immune system.
    • This information would then be used as a part of the adaptive immune system for a more efficient and more powerful immune response for future encounters with that antigen.
    • This subsequent amplification with improved specificity of immune response is known as secondary immune response.

  • Lymphoid Tissue

    • Lymphoid tissue consists of many organs that play a role in the production and maturation of lymphocytes in the immune response.
    • The lymphoid tissue may be primary or secondary depending upon its stage of lymphocyte development and maturation.
    • Secondary or peripheral lymphoid organs maintain mature naive lymphocytes until an adaptive immune response is initiated.
    • Mature lymphocytes ill then recirculate between the blood and peripheral lymphoid organs until they encounter the specific antigens where they perform their immune response functions.
    • Secondary lymphoid tissue provides the environment for the antigens to interact with the lymphocytes.

  • Active and Passive Humoral Immunity

    • The humoral immune response is the aspect of immunity mediated by secreted antibodies.
    • The humoral immune response (HIR) is the aspect of immunity mediated by secreted antibodies produced by B cells.
    • Active humoral immunity refers to any form of immunity that occurs as a result of the formation of an adaptive immune response from the body's own immune system.
    • Passive immunization is used when there is a high risk of infection and insufficient time for the body to develop its own immune response, or to reduce the symptoms of ongoing or immunosuppressive diseases.
    • This effect is usually overcome by secondary responses to booster immunization.

  • Immunodeficiencies

    • Most cases of immunodeficiency are acquired (secondary) but some people are born with a defective immune system, or primary immunodeficiency.
    • T-cell deficiency is often caused secondary disorders such as acquired immune deficiency syndrome.
    • Immunodeficiency often affects multiple components, with notable examples including severe combined immunodeficiency (which is primary) and acquired immune deficiency syndrome (which is secondary).
    • Distinctions between primary versus secondary immunodeficiencies are based, respectively, on whether the cause originates within the immune system itself or, in turn, is due to insufficiency of a supporting component of it, or an external decreasing factor of it.
    • HIV directly infects a small number of T helper cells, and also impairs other immune system responses indirectly.

  • Tonsils

    • The tonsils are small masses of secondary lymphoid tissue located in the pharynx.
    • The tonsils primarily facilitate adaptive immune responses in the upper respiratory tract, one of the most common pathways for pathogen entry in the body.
    • The secondary lymphoid tissue within the tonsils functions like the same type of the tissue in lymph nodes.
    • Captured antigens are presented to B and T cells within the tonsil, then the B cells migrate to germinal centers within the tonsil as an adaptive immune response is initiated.
    • It does not appear to cause weakened immune function.

  • Development of the Immune System

    • Maternal factors also play a role in the body's immune response.
    • These antibodies can also produce a negative response.
    • Passively acquired maternal antibodies can suppress the antibody response to active immunization.
    • Similarly the response of T-cells to vaccination differs in children compared to adults, and vaccines that induce Th1 responses in adults do not readily elicit these same responses in neonates.
    • There is evidence that these steroids act directly not only on the primary and secondary sexual characteristics, but also have an effect on the development and regulation of the immune system.

  • Lymphocytes

    • A lymphocyte is a type of white blood cell in the immune system, including both the B and T cells of the adaptive immune system and natural killer (NK) cells of the innate immune system .
    • Helper T cells (CD4s) facilitate the organization of immune responses, and can bind to MHC class II.
    • They have an immunosuppressive effect that inhibits cell-mediated immunity at the end of a response and destroys autoimmune T cells that aren't filtered out by negative selection in the thymus.
    • Memory T cells are created after an adaptive immune response subsides, retaining the presented antigen.
    • Mature B cells leave the thymus and travel to secondary lymphoid tissue such as the lymph nodes.

  • 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, antigen-specific immune response after the innate immune response fails to prevent a pathogen from causing an infection.
    • Helper T cells facilitate the immune response by guiding cytotoxic T cells to pathogens or pathogen-infected cells, which they will then destroy.
    • Humoral immunity refers to the component of the adaptive immune response that is caused by B cells, antibodies, and type 2 helper T cells (Th2), as well as circulating mast cells and eosinophils to a lesser extent.
    • This binding will cause degranulation and release of inflammatory mediators that start an immune response against the antigen.