An animal suitable as a model for an allergic disorder, wherein the animal is an immuno-modulated animal which has been sensitized with an antigen under a specific pathogen free environment such that when the animal displays allergy symptoms caused by the antigen.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments will now be described with reference to the accompanying drawings.

The animal of the present invention is suitable as a model for an allergic disorder, preferable as a model of a human allergic disorder. The animal is an immuno-modulated animal which has been sensitized with an antigen under a specific pathogen free environment (SPF environment) such that when the animal displays allergy symptoms caused by the antigen. Thus, the animal has been maintained under a specific pathogen free environment during which time the animal has been sensitized with the antigen.

The animal of the present invention is produced by maintaining the animal under a specific pathogen free environment. During this time, the animal is sensitized with the antigen. The animal is sensitized with the antigen for as long as necessary to produce allergy symptoms caused by the sensitizing antigen. The term "specific pathogen free environment" is well-recognized by those skilled in the art as referring to conditions in which the animal is not exposed to antigens other than the antigen used for sensitization. In this way, the allergy symptoms produced in the animal are specific for the sensitizing antigen.

In one embodiment, a specific pathogen free environment is set up according to the standard set by Japan Animal Association (See, for example, "SPF Animal: the standard for production and maintenance" 1995, published by Japan SLC, Inc., pages 15 20, the contents of which are incorporated herein by reference).

In one embodiment, the SPF environment is established such that temperature control is set at 23.+-.2.degree. C., humidity control is set at 55.+-.5%. These conditions may be automatically controlled by an air ventilation system. If the temperature falls out of this range or the humidity falls outside the range of 55.+-.10%, an alarm is programmed to sound. Ventilation is performed 15 to 20 times/hour, noise level is kept below 60 dB, light is at 150 to 600 Lx between 7:00 am and 7:00 pm and the air quality level is maintained at class 10,000 according to the NASA standard. A description of a procedure for maintaining such an air quality level is described in Guide for the Care and Use of Laboratory Animals, National Research Council, Institute of Laboratory Animal Resources Commission on the Life Sciences, National Academy Press, Washington, D.C., 1986, incorporated herein by reference in its entirety, at page 76. The biologically permissible range for the temperature is 20 26.degree. C. and 40 70% for the humidity.

Preferably, the animal is a non-human mammal. In this embodiment, the animal may be mouse, rat, guinea pig, rabbit, dog, cat, cow, sheep, or pig. A mouse or a rat is particularly preferred.

As used herein the term "immuno-modulated experimental animal" refers to experimental animal, i.e., an animal customarily used for testing in medical and/or cosmetic research, with some type of immune deficiency or abnormality. Examples of such animals are well-known to those skilled in the art. Examples include an LEC rat, BN/Crj rat, NC/Nga mouse, MRL/1pr mouse, NZW mouse, NBZ mouse, NZW/B F1 mouse. Preferably, it is an experimental animal of a Th 2 kind, because during immune reaction, Th2 (helper T cell 2) dominantly reacts and secretes IL-4, IL-5 and IL-10. In particular, NC/Nga mouse and BN/Crj rat are known as an experimental animal of a Th 2 kind, and are particularly preferred animals in the present invention. A NC/Nga mouse is particularly preferred.

The nature of the antigen is not particularly limited in the present invention, and a wide variety of different types of antigenic materials may be used. Suitable antigens invention include natural compounds, including extracts from natural substances, such as poke weed mitogen, mite, pollens including the pollens from Japanese cedar, dandruff, fur and feather from dogs, cats, mice and rats, among others.

The allergic disorder for which the animal may serve as a model is not particularly limited. Examples of the allergic disorder include atopic dermatitis, atopic asthma, conjunctival allergy, allergic rhinitis, food allergy, urticaria, contact dermatitis, allergic reactions to drugs, and anaphylaxis.

Preferably, the antigen is sensitized by injecting the antigen, a solution and/or suspension thereof, into the skin of the animal. Preferable locations for such injections is the skin of the abdominal cavity or the skin proximal to the ears of the animal. The antigen is preferably injected into the skin on a daily basis until the allergy symptoms appear on the skin surface of the animal. A suitable time period for sensitizing the animal with the antigen is 5 to 50 days. This range includes all specific values and subranges therebetween, such as 8, 10, 15, 20, 25, 30, 35, 40 and 45 days.

The animal of the present invention is particularly useful for method screening an agent for effectiveness against an allergic disorder. In this embodiment, at least one agent is applied the animal at the site of the allergy symptom (topical administration) or administered to the animal orally. Then, it is determined whether the agent reduced the allergy symptom and/or in vitro disorder. If administering the agent causes a reduction in the allergy symptom and/or in vitro disorder, this result is correlated a with effectiveness against the allergic disorder. If the agent does not cause a reduction in the allergy symptom and/or in vitro disorder, this result is correlated with ineffectiveness against the allergic disorder. In a preferred embodiment, multiple agents are screened using this procedure.

Any of the well-known methods can be used to determine whether an agent is effective in reduced the allergy symptom and/or in vitro disorder. Examples of these methods include (a) Measurement of affected areas, particularly measurement of the ventral sides of the ears of the animal, (b) measurement of anti-Dp-specific IgG levels, (c) measurement of cytokine concentration, (d) histological analysis: degranuation of mast cell, (e) histological analysis: eosinophil infiltration in atopic dermatitis (see J. Invest. Dermatol. 100, 137, incorporated herein by reference).

This screening method is also useful in evaluating a cytokine production inhibitor. Therefore, once an agent has been identified by this screening method, it may be administered to patients in need thereof. In a preferred embodiment, the patient is a human. Examples of conditions that may be treated using an agent identified in the inventive screening process include organ or tissue allo- or xeno-transplant rejection, e.g., kidney, liver, heart, lung, combined heart-lung, bone marrow, islet cells, pancreatic, skin, chromaffin or dopamine producing cells, small bowel, or corneal transplantation. Treating and/or preventing graft-versus-host disease, such as one which occurs following bone marrow transplantation.

The present invention also provides a method of screening for an agent for effectiveness in preventing an allergic disorder, comprising: applying at least one agent to the an immuno-modulated experimental animal, sensitizing the animal with an antigen, determining whether the agent prevents an allergy symptom and/or in vitro disorder in the animal, correlating prevention of the allergy symptom and/or in vitro disorder with effectiveness for preventing the allergic disorder, and correlating prevention of the allergy symptom and/or in vitro disorder with ineffectiveness for preventing the allergic disorder.

The ability of an agent to prevent an allergic disorder is determined by whether the agent is effective in preventing symptoms of the allergic disorder. This can be determined by the same methods described for determining whether an agent is effective for reducing the allergy symptom described above.

In the context of the present invention, suitable patients for treatment with the agents identified by the inventive methods include humans and animals. Non-human mammals are the preferred animal patients.
 

Claim 1 of 16 Claims

1. An NC/Nga mouse that has been sensitized with a mite extract by multiple sequential injections of mite antigen over a period 18 days or less in a pathogen-free environment, wherein said mouse exhibits at least one symptom of severe dermatitis in a shorter period of time than a conventional NC/Nga mouse; or wherein said mouse develops dermatitis lesions sufficiently severe for evaluating the effectiveness of a medicine by day 18.
 

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