ASTHMA/ALLERGY SIG REPORT (P-1)

ASTHMA/ALLERGY SIG REPORT

IMMUNOTHERAPY (Isaac Bromberg)

WHAT IS IMMUNOTHERAPY?

Immunotherapy is a preventative treatment for sufferers of both localized and systemic anaphylaxis. Usually, allergen is administered via injection in gradually increasing doses, up to a set level, after which a fixed maintenance dose is continued. In some trials and treatments, the initial doses increase rapidly over a number of hours or days. This is known as 'rush' immunotherapy. Individuals treated with immunotherapy show decreased sensitivity to allergens with long term effectiveness (up to 18 months after treatment). (1)

HOW DOES IMMUNOTHERAPY WORK?

Studies using various allergens show definite changes in immune system response after immunotherapy treatment. After a rush insect venom immunotherapy trial, in addition to a decrease in response to venom challenge, treated individuals responded with a decrease in IL-4 production and an increase in IFN-gamma production (among other changes) indicating a shift in cytokine production from a TH2 to a TH1 distribution. (2) Experiments using dust mite antigen also describe an increase in IFN-gamma production. (3) Some studies show a decrease in both INF-gamma and IL-4, however, and some describe subjective improvements, but no changes in immune-active components. (4, 5)

ARE THERE RISKS INVOLVED?

Because some individuals undergoing immunotherapy suffer from severe systemic anaphylactic reactions, it is possible for the therapy to in fact precipitate an untoward effect. In most cases, persons going through immunotherapy (especially rush protocols) are closely monitored to ensure that they tolerate the antigen. The safety of rush immunotherapy has been demonstrated for a variety of antigens which cause a range of reactions. (6)

WHAT'S NEW IN IMMUNOTHERAPY?

Studies investigating new allergen delivery approaches have had mixed results. An attempt to evaluate sublingual (SL) administration of allergen as compared to subcutaneous injection, which is the most common route, showed no immunological response to the SL administration. However, patients treated this way reported feeling less allergy symptoms and lower use of medications. (7)

Another interesting trial investigated the effect of active culture yogurt on symptoms of individuals suffering from allergic asthma. The only noticeable effect of this 'therapy' was a nominal increase in IFN-gamma production by lymphocytes stimulated with concanvalin-A (a mitogenic lectin). Treated individuals reported no change in symptoms. (8)

An evaluation of the use of peanut extract in immunotherapy treatments for individuals with immediate hypersensitivity reactions to ingested peanuts showed increased tolerance to the allergen after a course of rush injections followed by maintenance doses. Unfortunately, nearly all individuals involved suffered from repeated systemic reactions to the treatment. The investigators in this trial feel that the development of a modified peanut extract is necessary before further study is undertaken. (9)

1. Pichler, C. E., et al. 1997. Specific immunotherapy with Dermatophagoides pteronyssinus and D. farinae results in decreased bronchial hyperreactivity. [Abstract] Allergy 52(3): 274-283.
2. Bellinghausen, I., et al. 1997. Insect venom immunotherapy induces interleukin-10 production and a Th2-to-Th1 shift, and changes surface marker expression in venom-allergic subjects. [Abstract] Eur J Immunol 27(5): 1131-1139.
3. Lack, G., et al. 1997. Rush immunotherapy results in allergen-specific alterations in lymphocyte function and interferon-gamma production in CD4+ T cells. [Abstract] J Allergy Clin Immunol 99(4): 530-538.
4. O'Brien, R. M., et al. 1997. House dust mite immunotherapy results in a decrease in Der p 2-specific IFN-gamma and IL-4 expression by circulating T lymphocytes. [Abstract] Clin Exp Allergy 27(1): 46-51.
5. Olsen, O. T., 1997. A 1-year, placebo-controlled, double-blind house-dust-mite immunotherapy study in asthmatic adults. [Abstract] Allergy 52(8): 853-859.
6. van der Brempt, X., et al. 1997. Accelerated desensitization for hymenoptera venom allergy in 30 hours: efficacy and safety in 150 cases. [Abstract] [Article in French] Rev Med Brux 18(3): 120-124.
7. Quirino, T., et al. 1996. Sublingual versus injective immunotherapy in grass pollen allergic patients: a double blind (double dummy) study. [Abstract] Clin Exp Allergy 26(11): 1253-1261.
8. Wheeler, J. G., 1997. Immune and clinical impact of Lactobacillus acidophilus on asthma. [Abstract] Ann Allergy Asthma Immunol 79(3): 229-233.
9. Nelson H. S., 1997. Treatment of anaphylactic sensitivity to peanuts by immunotherapy with injections of aqueous peanut extract. [Abstract] J Allergy Clin Immunol 99(6 Pt 1): 744-751.