associated with atopic dermatitis in children with cat allergies. Symptoms Symptoms of an allergic reaction to cats range from mild to severe, and include swollen, red, itchy, and watery eyes, nasal congestion, itchy nose, ear pain similar to pain caused by an ear infection, sneezing, chronic sore throat or itchy throat, coughing, wheezing, asthma, hay fever, hives or rash on the face or chest, or itchy skin. If a cat has scratched, licked, or bitten someone who is allergic to cats, redness and sometimes even swelling of the affected area will occur. For those severely allergic, a reaction may resemble that of someone with a severe food allergy, and such reactions require emergency medical care. Pathophysiology As the allergen enters through the nose or mouth, antigen cells analyze the allergen and present antigenic peptides to helper T cells. The helper T cells acquire a type 2 phenotype (Th2) and stimulate plasma cells to produce IgE due to the presence of specific cytokines. If Th2 is expressed too much, the symptoms of cat allergies appear. Inhaled cat allergens will activate mast cells, causing coughing, increased mucous production, and airway constriction. Treatments Medications Cat allergies can often be controlled with over the counter or prescription medications. Antihistamines and decongestants may provide allergy relief. Immunotherapy injections Some people with allergies find relief in allergen immunotherapy, a periodic injection therapy designed to suppress the body's natural immune responses to the cat allergens. In its early stages, AIT utilized cat dander extract, which consists of microscopic dry skin flakes of cats, but later resorted to Fel d 1 due to issues of standardization. One way researchers use Fel d 1 in immunotherapy is through the alteration of its chemical structure. Disulfide bonds between Fel d 1 chains were broken to reduce the binding between the allergen and immunoglobulin E (IgE), inhibiting an allergic response. Cat bathing Regularly bathing a cat may remove significant amounts of allergens from fur. After bathing, the levels of Fel d 1 on cat skin and fur return within two days of bathing. In addition, amounts of Fel d 1 in the surrounding air return after a 24-hour period of bathing the cat. Feeding the cat a high quality diet with plenty of omega-3 fatty acids will help keep the coat healthy and minimize dander. Development of other treatments Development of several human vaccines have been abandoned, including Allervax and Cat-SPIRE.