delayed hypersensitivity

(noun)

the reaction takes two to three days to develop

Related Terms

Examples of delayed hypersensitivity in the following topics:

  • Hypersensitivity

    • A hypersensitivity reaction refers to an overreactive immune system triggered by allergies and autoimmunity.
    • Hypersensitivity (also called hypersensitivity reaction) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity, and are commonly mediated by antibodies.
    • Hypersensitivity reactions require a pre-sensitized (immune) state of the host .
    • Delayed Hypersensitivity (Type IV) is an immune response to foreign substances that occurs over the course of several hours.
    • The common effects of Poison Ivy are the result of Type IV hypersensitivity.

  • Hypersensitivities

    • The types of hypersensitivities include immediate, delayed, and autoimmunity hypersensitivities.
    • A large proportion of the population is affected by one or more types of hypersensitivity.
    • Delayed hypersensitivity is a cell-mediated immune response that takes approximately one to two days after secondary exposure for a maximal reaction to be observed.
    • This type of hypersensitivity involves the TH1 cytokine-mediated inflammatory response.
    • Delayed hypersensitivity occurs in some individuals in response to contact with certain types of jewelry or cosmetics.

  • Type IV (Delayed Cell-Mediated) Reactions

    • Type IV hypersensitivity reactions are cell-mediated and take 2 to 3 days to develop.
    • Type IV hypersensitivity is often called delayed type hypersensitivity as the reaction takes two to three days to develop.
    • A classic example of delayed type IV hypersensitivity is the Mantoux tuberculin test in which skin induration indicates exposure to tuberculosis.

  • Primary Immunodeficiency Diseases

    • Generally, the symptoms and signs that lead to the diagnosis of an immunodeficiency include recurrent or persistent infections, or developmental delay as a result of infection.
    • Tests for T cell function: skin tests for delayed-type hypersensitivity, cell responses to mitogens and allogeneic cells, cytokine production by cells

  • Type II (Cytotoxic) Reactions

    • In type II hypersensitivity (or cytotoxic hypersensitivity), the antibodies produced by the immune response bind to antigens on the patient's own cell surfaces.
    • Another form of type II hypersensitivity is called antibody-dependent cell-mediated cytotoxicity (ADCC).
    • Autoimmune diseases resemble type II-IV hypersensitivity reactions.
    • They differ from hypersensitivity reactions in that the antigens driving the immune process are self-antigens rather than non-self as in hypersensitivity reactions.
    • Below are some examples of Type II hypersensitivity-like autoimmunity.

  • Allergies

    • An allergy is a hypersensitivity disorder of the immune system.
    • Allergy is one of four forms of hypersensitivity and is formally called type I (or immediate) hypersensitivity.
    • If an immuno-response is seen, it can be concluded that the patient has a hypersensitivity (or allergy) to that allergen.

  • Type III (Immune Complex) Reactions

    • Type III hypersensitivity occurs when there is little antibody and an excess of antigen, leading to the formation of small immune complexes.
    • It is characterized by solvent antigens that are not bound to cell surfaces (which is the case in type II hypersensitivity).
    • Hence, vasculitis, glomerulonephritis and arthritis are commonly-associated conditions as a result of type III hypersensitivity responses.
    • Skin response to a hypersensitivity of this type is referred to as an Arthus reaction, and is characterized by local erythema and some induration.
    • This is the third form of hypersensitivity in the Gell-Coombs classification, called Type III hypersensitivity.

  • Immune Complex Autoimmune Reactions

    • This is the third form of hypersensitivity in the Gell-Coombs classification, called Type III hypersensitivity.
    • In immunology, the Arthus reaction is a type of local type III hypersensitivity reaction.
    • Type III hypersensitivity reactions are immune complex-mediated.
    • Typical of most mechanisms of the type III hypersensitivity, Arthus manifests as local vasculitis due to deposition of IgG-based immune complexes in dermal blood vessels.

  • Type I (Anaphylactic) Reactions

    • Type I (or immediate/anaphylactic) hypersensitivity can be caused by the body's response to a foreign substance.
    • Type I hypersensitivity is also known as immediate or anaphylactic hypersensitivity.

  • Practice 3: Test of a Single Variance

    • Suppose an airline claims that its flights are consistently on time with an average delay of at most 15 minutes.
    • It claims that the average delay is so consistent that the variance is no more than 150 minutes.
    • Doubting the consistency part of the claim, a disgruntled traveler calculates the delays for his next 25 flights.
    • The average delay for those 25 flights is 22 minutes with a standard deviation of 15 minutes.
    • If an additional test were done on the claim of the average delay, which distribution would you use?