Q:

4/29/2013
I have a patient who is a college student/research assistant and works with rats. He has congestion and sneezing with exposure and wheezes at night after being in the lab. His IgE for rat urine was 27.10. Are there any studies about rat immunotherapy that I could use to attempt desensitization for this patient?

A:

Thank you for your inquiry.

I have no personal experience with immunotherapy to rat allergen, and I was only able to find two previous articles in the literature describing successful allergen immunotherapy to rat allergen. The abstracts of these articles are copied for you below.

Thank you again for your inquiry and we hope this response is helpful to you.

Laryngorhinootologie. 2004 Aug;83(8):512-5.
[Specific immunotherapy in inhalative allergy to rat epithelium].
[Article in German]
Hansen I, Hörmann K, Klimek L.
Source
HNO-Universitätsklinik Mannheim, Ruprecht-Karls-Universität Heidelberg.
Abstract
Background: The only causal treatment that can be offered to allergic patients apart from allergen avoidance is specific immunotherapy. Its efficacy depends on the specific allergen the patient is allergic to, the quality of the extract, the total amount of allergen administered to the patient and the administration schedule.
Methods and Patient: Our patient suffered from inhalative allergy to rat epithelium with severe rhinoconjunctivitis and bronchial asthma. She regularly worked with laboratory rats as a biologist. A job-shift was impossible for the patient, and so was allergen avoidance. We therefore decided to treat the patient with specific immunotherapy. Treatment was performed as in-patient procedure with Rush-Immunotherapy in dosage increase phase. Maintenance injections were administered as out-patient.
Results: As early as some months after induction of the therapy, the patient felt subjective symptom relief, blood samples taken revealed decrease of total IgE and specific IgE towards rat epithelium. Therapy was continued for 18 months, specific IgE against rat epithelium could not be detected any more. The patient does not claim any allergy symptoms when working in the rat laboratory any more.
Conclusions: Even in unusual allergies, specific immunotherapy can be indicated. In our patient, specific immunotherapy to rat epithelium lead to complete symptom relief and enabled the patient to practise her profession without restraints.

J Allergy Clin Immunol. 1980 Jun;65(6):413-21.
Efficacy and specificity of immunotherapy with laboratory animal allergen extracts.
Wahn U, Siraganian RP.
Abstract
The clinical and immunologic response to immunotherapy with laboratory animal allergens was evaluated. There were 23 patients; 11 had received immunotherapy with 12 different extracts (five mouse, six rat, one rabbit), and 12 were matched untreated patients. As a group, nine of 23 had seasonal hay fever. Among the treated patients nine of 11 subjectively improved with immunotherapy. Blocking antibody titers were determined by serum inhibition of allergen-induced histamine release. Treated patients had mean blocking antibody levels of G30 = 59.3 +/- 38.7. In the untreated patients the antibody level was low (G30 = 4.6 +/- 3.6). The difference between the two groups was highly significant (t test p less than 0.001). The blocking antibody level correlates with both the final weekly allergen dose and also the cumulative allergen dose received during immunotherapy. When pretreatment sera were available a temporal rise in blocking antibody was demonstrated during immunotherapy. In patients allergic to several laboratory animals and treated with one allergen, the blocking antibody response was predominantly specific to the allergen used in immunotherapy. This indicates a lack of cross-reactivity in the IgG response to the major animal allergens. When immunotherapy was discontinued in four patients there was a dramatic decrease in the blocking titer, and after 24 mo the levels were the same as those of untreated patients.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology