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DNFB-Induced DTH in Mice and Rats

Delayed type hypersensitivity (DTH), also known as cell mediated immune memory response or type IV hypersensitivity is characterized by erythema and induration at the site of contact in sensitized humans or animals. It is involved in the pathogenesis of many infectious diseases (tuberculosis, leprosy, blastomycosis, histoplasmosis, toxoplasmosis, leishmaniasis, etc.), autoimmune diseases and granuloma due to infection of foreign antigens. Another form of DTH is the contact dermatitis caused by poison ivy, chemicals or heavy metals, etc. Systemic injection of an antigen in an animal results in fever, synthesis of acute phase proteins and death in some instances. The histology of DTH can be different for different species, but in general it is characterized with an influx of immune cells at the site of injection, either macrophages and basophils in human and mice or neutrophils in guinea pigs and induration which becomes apparent within 24-72 hours. T cells (either CD4+ or CD8+ depending on the antigen) are required to initiate the reaction even though they make up only a small fraction (10-20%) of the inflammatory infiltrates. Cytokines secreted by helper T cells (monocyte chemotactic factor, interleukin-2, interferon γ, TNFα/β) represent the early hallmarks of the inflammation. However, it remains unclear whether the recruitment of other immune cells to the site of challenge is directly regulated by T cells.

PharmaLegacy Research Tools
Rodent model characteristics:

·       Peak response at 24-48h, rare erythema and different numbers of lymphocytes/monocytes across different models

·       High throughput and requirement for smaller quantity of compound

·       Low variability between subjects using inbred animals

·       Higher concentration of antigen/hapten for induction in certain strains


Measurement of inflammatory responses and molecular pharmacology:

·       Ear/paw swelling

·       Myeloperoxidase assay (neutrophils and granulocytes)

·       Cytokine production: TNFα, interferon γ, IL-1β, IL-4, IL-6, Cox-2, (ELISA or Q-PCR)


Histopathology:

·         H&E staining: induration and infiltrations

·         Immunohistochemistry: specific T cell response and cell proliferation


Pharmalegacy has three types models of DNFB-induced DTH:

·       DNFB-induced DTH in ICR mice (preventive or therapeutic)

·       DNFB-induced DTH in wistar rats

·       DNFB-induced DTH in BALB/c mice


DNFB-induced DTH in wistar rats

Aim: To examine the effect of dexamethasone on DNFB-induced DTH in Wistar rats

Animal:  Wistar rats, male,180-200 g

Reagent: DNFB and Dexamethasone, Acetone, Olive oil, Dexamethasone tablet



Effect of Dex on Ear Thickness and MPO activity

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Effect of Dex on IL-1b, IL-6, and TNF-a mRNA in Ears

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Ear Pathology (H & E Staining)image.png




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