The WHO immunotherapy position paper on allergen immunotherapy published in
June, 1998, introduces the term "vaccine" instead of "allergen extract". T
his fact may be regarded a recognition of the level of modern standardizati
on reflecting the continuing refinement of allergen technology. Standardiza
tion of allergen vaccines includes the exact characterization of the allerg
en content, the quantification of the major allergens and a constant allerg
enic potency. Allergen vaccines are applied for the treatment of patients a
s aqueous or depot preparations of intact or chemically modified allergens.
While all epitopes are conserved in intact allergen vaccines the chemical
modification induces a selective destruction of lysine-containing epitopes
resulting in a larger patient to patient variation of the response to the a
llergen vaccine.