Delayed-type hypersensitivity DTH reaction

It is also more or less accepted that T-cells, in particular T-helper cells (CD4+), may develop into either Thl cells or Th2 cells. By doing so, T-helper cells orchestrate the ensuing immune response by the types of cytokines they produce. Thl cells, by producing IL-12 and y-IFN, stimulate macrophages and/or cytotoxic T-cells to kill and destroy infected or malignant cells, or to initiate a delayed type hypersensitivity (DTH) reaction Th2 cells, by producing IL-4, IL-5, IL-10, IL-13, trigger B-cells to initiate antibody production. 

For keyhole limpet hemocyanine (KLH) both antibody responses and delayed type hypersensitivity (DTH) reactions can be determined [43—45]. In addition several infectious models, including bacterial, viral and parasitic infections may be used to challenge the immune system [18,46]. As survival and eradication of the infections is the primary function of the immune system, these models provide direct information on the functional status of the immune system. Direct immunotoxic compounds will induce immunosuppression and thus an increase in infection rate and/or severity of the infection. The number of infectious agents (bacteria, parasites, or viral colonyforming units), increased morbidity and mortality are indications for an immunotoxic effect. Also a reduction in specific antibody levels in animals treated with the test compound compared to nontreated controls indicates immunosuppression. 

In the present report, we describe the genetic constmcdon, expression, and cell receptor targeted toxicity of a fusion protein composed of the first 485 amino acids of diphtheria toxin linked to amino acids 2 through 133 of IL-2. The fusion protein, IL-2-toxin, is shown to be selectively toxic toward high affinity IL-2 receptor bearing cells in vitro, and to block an activated T-ceU mediated delayed type hypersensitivity (DTH) reaction in vivo. 

Type IV Delayed-type Hypersensitivity (DTH). Delayed-type hypersensitivity reactions are T-cell mediated with no involvement of antibodies. However, these reactions are controlled through accessory cells, suppressor T cells, and monokine-secreting macrophages, which regulate the proliferation and differentiation of T cells. The most frequent form of DTH manifests itself as contact dermatitis. The drug or metabolite binds to a protein in the skin or the Langerhans cell membrane... 

Toxicology. NRL causes allergic skin reactions of type I (immediate-type) and type IV [delayed-type hypersensitivity (DTH)]. 

Toxicology. Zinc dithiocarbamates (ZDC) are contact allergens and are one of the chemical groups in rubber that cause the type IV delayed-type hypersensitivity skin reaction (DTH). ... 

However, there are times when the immune system acts in an exaggerated manner leading to tissue damage. This is referred to as hypersensitivity. In the classic Coombs and Cell classification system, there are four types of hypersensitivity reactions. The first three (types 1-3) are mediated by antibody (e.g., IgG, IgE). The fourth type (type 4) is mediated by antigen-specific T cells and is also known broadly as delayed-type hypersensitivity (DTH). It is delayed because the reaction appears hours to days after antigen crosses into the skin. Though often thought of as... 

There are four main types of hypersensitivity reactions type I, II, and III hypersensitivity reactions are associated with the production of antibodies while type IV is cell mediated. Immediate hypersensitivity (type I) is due to IgE elicited by the antigen that binds to Fee receptor of mast cells or eosinophils, leading to their activation. Asthma due to platinum salts might be due to specific IgEs that have been found in sensitized patients. In addition, it seems that this agent triggers IgE production in rats (Pepys 1983). However, to our knowledge, this model has not been extensively studied. Type IV or delayed type hypersensitivity (DTH) is probably due to THl cells and is probably frequently involved in metal-mediated adverse side reactions. 

The delayed type hypersensitivity response (DTH) is an assay frequently used to assess the T cell response to commonly encountered microbial antigens. It involves intradermal injection of antigens to which the majority of individuals are immune (known as recall antigens) such as vaccinia, herpes simplex, and mumps viruses, Candida, and tetanus toxoid. In normal individuals, after 24-48 hours, an inflammatory filtrate results in local edema and induration, the diameter of which can be measured. A negative reaction to all the antigens (anergy) is usually reflected by decreased lymphocyte function as measured in vitro and is frequently seen in AIDS and ARC patients. 

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