Thank you for your inquiry.
The best review, of which I am aware, of this issue was published by Calderon, et al. (abstract copied below). Dr. Hal Nelson also touched on this issue in an article appearing in Current Opinion in Allergy and Clinical Immunology (abstract copied below).
From studies in the older literature, it is known that allergen immunotherapy using an allergen to which the patient has no sensitivity can cause sensitization as manifested by the development of a positive skin test to the allergen (1, 2).
However, in the studies that I could find, this sensitization was not associated with clinical reactivity. That is, although the patients developed positive skin tests, they did not develop symptoms to the newly sensitized allergen.
Thank you again for your inquiry and we hope this response is helpful to you.
J Allergy Clin Immunol. 2012 Apr;129(4):929-34. doi: 10.1016/j.jaci.2011.11.019. Epub 2012 Jan 11.
Multiple-allergen and single-allergen immunotherapy strategies in polysensitized patients: looking at the published evidence.
Calderón MA, Cox L, Casale TB, Moingeon P, Demoly P.
Imperial College-National Heart & Lung Institute, Royal Brompton Hospital, London, UK.
In allergen immunotherapy there is debate as to whether polysensitized patients are best treated with many allergens simultaneously (chosen according to the sensitization profile, a predominantly North American approach) or a single allergen (chosen according to the most clinically problematic allergy, a predominantly European approach). In patients seeking treatment for moderate-to-severe respiratory allergies, polysensitization is more prevalent (range, 50% to 80%) than monosensitization in both the United States and Europe. Safe, effective, single-allergen preparations will most likely have been tested in polysensitized patients. In robust, large-scale clinical trials of grass pollen sublingual tablets, polysensitized patients benefited at least as much from allergen immunotherapy as monosensitized patients. A recent review of multiallergen immunotherapy concluded that simultaneous delivery of multiple unrelated allergens can be clinically effective but that there was a need for additional investigation of therapy with more than 2 allergen extracts (particularly in sublingual allergen immunotherapy). More work is also required to determine whether single-allergen and multiallergen immunotherapy protocols elicit distinct immune responses in monosensitized and polysensitized patients. Sublingual and subcutaneous multiallergen immunotherapy in polysensitized patients requires more supporting data to validate its efficacy in practice.
Curr Opin Allergy Clin Immunol. 2009 Dec;9(6):549-53. doi: 10.1097/ACI.0b013e328330ee69.
Specific immunotherapy with allergen mixes: what is the evidence?
National Jewish Health, Denver, Colorado 80206, USA.
Purpose of Review: The purpose is to review the published evidence for the use of multiallergen mixes in subcutaneous and sublingual immunotherapy.
Recent Findings: Data are drawn from published articles and reviews, including a recent complete search of the English and non-English literature for publications on multiallergen immunotherapy.The problems arising from dilution of extracts and degradation of extracts resulting from adding additional extracts to a mixture are confirmed. The published literature of the use of multiallergen extracts in subcutaneous and sublingual immunotherapy indicates that multiallergen extracts are effective when given by injection, but a similar efficacy has not been established for them when administered sublingually.
Summary: Multiallergen extract mixes are probably effective for subcutaneous immunotherapy provided attention is paid to the concentration of each allergen in the mix and mixing of protease containing extracts with pollen and dander extracts is avoided. Further studies are needed to determine if multiallergen mixes are effective in sublingual immunotherapy.
1.The sensitizing effects of emulsified pollen antigens in atopic subjects naturally sensitive to an unrelated antigen; Journal of Allergy, Volume 33, Issue 4, July–August 1962, Pages 285–294; Samuel M. Feinberg, M.D., et al
2.Sensitization of human subjects after multiple intracutaneous injections of aqueous ragweed extract. Journal of Allergy, Volume 40, Issue 5, November 1967, Pages 269–274. John T. Connell, M.D.
Phil Lieberman, M.D.