Passive Cutaneous Anaphylaxis Models
As a leading pharmaceutical contract research organization (CRO), Creative Animodel offers a wide range of in vivo pharmacology services for drug screening and assessment. Our company generates animal models of passive cutaneous anaphylaxis (PCA) to test the efficacy of anti-inflammatory drug candidates.
PCA and Type I Hypersensitivity
PCA is an immediate dermal response mediated by the cross-linking of allergens to IgE on the surface of mast cells and basophils. It belongs to type I hypersensitivity reaction and is characterized by increased permeability of vessels within the skin.
Figure 1. General mechanism underlying an immediate type I hypersensitivity reaction. (Kindt, et al. 2000)
Type I Hypersensitivity is an allergic reaction caused by re-exposure to a specific type of antigen. During sensitization process, B cells are stimulated to produce immunoglobulin E (IgE) antibodies specific to an antigen, then the IgE antibodies bind to receptors on the surface of tissue mast cells and blood basophils. The antigen cross-links the IgE antibodies, resulting in degranulation and the secretion of pharmacologically active mediators such as histamine, leukotriene, and prostaglandin. These products can affect vasodilation and smooth-muscle contraction.
PCA Models at Creative Animodel
Creative Animodel provides rat and mouse models of PCA to study the dermal sensitivity to allergens and drug efficacy in hypersensitivity reaction. Changes in vascular permeability and plasma extravasation after antigen challenge are important indexes to be measured. Evans Blue dye is injected intravenously along with the antigen to visualize and quantify the allergic responses. The workflow to generate PCA models is shown below.
Figure 2. The inhibitory effect on anti-DNP IgE-induced PCA in Balb/c mice.
One ear of the animal is injected with IgE antibodies, and the other is left alone. The IgE can bind to the surface of mast cells 3-5 hours later. Then the animal is given a tail vein injection of Evans Blue dye followed by a second tail vein injection of antigens. An interaction occurs between antigens and IgE on the injected ear and a local cutaneous allergic reaction appears due to the free histamine and other factors. The vascular permeability is increased and blood plasma containing the blue dye is leaking to the tissue, resulting in blue spots on the skin. One hour after the last injection, the animal is euthanized and both ears are harvested to quantify Evans Blue in the ear tissue. The diameter and quality of a blue spot indicate reaction intensity. The administration of therapeutic compounds is performed according to the schedule in this protocol.
• A wide range of animal models
• Outstanding and experienced scientists
• Comprehensive services for preclinical drug trials
• Reliable data and results
• Rapid turnaround and cost-effective
Creative Animodel is devoted to providing the best in vivo pharmacology services to help with your drug research and development. In addition to the animal models shown on our website, customized models are also provided to meet your special requirements. If you have any needs or questions, please don’t hesitate to contact us.
1. Goldsy, R.A.; et al. Immunology 5th Ed. W.H. Freeman, 2000.