ASTHMA/ALLERGY SIG REPORT (P-2)

VACCINES (Melissa Carlson)

ARE VACCINES THE KEY TO WINNING THE BATTLE AGAINST ALLERGIES AND ASTHMA?

Allergies and asthma afflict numerous people throughout the world. The incidence of allergy and asthma cases has been steadily increasing over the past few years. For this reason many researchers and patients sense the vital necessity to bring relief to the millions who suffer. As a result, scientists are progressing towards the development of vaccines against allergies and asthma.

One study at the University of Uppsala is focused on vaccinating against IgE, the immunoglobulin responsible for allergies and asthma. Researchers hope to reduce the levels of IgE production. A fusion protein was made that contained the constant domains two and three of rat IgE fused to an E. coli protein. When this fusion protein was injected into rats along with an adjuvant, a strong autoimmune anti-IgE response formed. Furthermore, when injected into rats sensitized to ovalbumin, serum IgE levels dramatically diminished. Also, histamine was not released from mast cells and basophils when later challenged by an allergen. However, the researchers discovered an obstacle to conquer, rats with very high IgE levels had an inadequate autoimmune response to the vaccinations. The vaccine's reliability is dependent upon the levels of IgE before the vaccination (1). Another study involves DNA immunization. An allergen gene from a house dust mite was placed into a vector and introduced into mice. IgG antibodies were formed as a response, but not IgE. This meant that IgE responses to IgE specific allergens may be suppressed (2). Also, another experiment showed immunization of mice with plasmid DNA inhibited IgE antibody formation. It was concluded that the CD4+ and CD8+ T cells from these immunized mice induced a T helper one response. This influenced the T helper two response and also down-regulated IgE formation (3, 4).

In addition, peptide vaccines are making big waves on the allergy and asthma research frontier. A peptide vaccine is a small piece of protein from an allergen that is injected into the patient. Such allergens are, grasses, dust mites, and ragweed (5). One such vaccine is ALLERVAX Ragweed, produced by the Immunologic Corporation in Massachusetts. It was shown to lessen ragweed allergy symptoms and reduce patient's use of allergy medication (6). Development of monoclonal antibodies specific for IgE is another line of research scientists are advancing towards. This monoclonal antibody will bind to the Fc portion of IgE and inhibit it from binding and activating mast cells. Through use of this monoclonal antibody more allergen was needed to stimulate an asthmatic response (7). Along similar lines, scientists have made a connection between viral infections and allergies and asthma. It appears that weak infections can stimulate the production of IgE. One such virus is the influenza virus. Therefore, researchers believe that vaccines to these viruses could be a way to stop the over production of IgE (8,9) These research focuses all show tremendous promise. The development of an allergy and asthma vaccine would ease millions from their relentless suffering.

1. Hellman, L. Is vaccination against IgE possible? Adv Exp Med Biol 1996;409:337-342.
2. Hsu, Ch., et al. Inhibition of specific IgE response in vivo by allergen-gene transfer. Int Immunol 1996 Sep;8(9):1405-1411.
3. Raz, E. et al. Preferential induction of a Th1 immune response and inhibition of specific IgE antibody formation by plasmid DNA immunization. Proc Nat Acad Sci USA 1996 May 14;93(10):5141-5145.