Using immunoblot studies, detailed antibody patterns were performed with the sera of 10 yellow jacket allergic patients undergoing specific immunotherapy with a yellow jacket venom SQ-depot extract (ALK, Denmark). Five males and five females (age range 10–65, mean 48 years) were investigated. All patients had a history of systemic reactions after an insect sting and a positive skin-prick test at a dose of at least 100 μg/ml yellow jacket venom.
Yellow jacket venom (ALK) was separated on a 7.5–20% SDS–PAGE, transferred to nitrocellulose (NC), and then the NC-strips were incubated with the patients’sera. For detection of IgE, IgG, IgG1 and IgG4, an alkaline phosphatase linked 2nd antibody was used. Prior to immunotherapy, a strong IgE binding was detected at 25 kD in nine of 10 patients, representing Antigen-5 (Ag-5) as major allergen. Reactivity to this antigen was also present with the other immunoglobulin classes, although not as marked. In addition, a second frequent IgG and IgG1-binding band was seen at 35 kD (phospholipase A). Only weak or no binding to this band was found with IgE and IgG4. Binding to hyaluronidase (43 kD) was seen only in three cases.
During immunotherapy, a significant increase in IgG and particularly IgG4 staining was found with Ag-5, whereas hyaluronidase induces mainly an IgG1 response and phospolipase A showed only a weak IgG response. In addition, the formation of new IgG4 binding to proteins in the region of about 70–90 kD was found in most patients. The dose necessary for the induction of this antibody formation was ≥ 150.00 SQ yellow jacket venom. We conclude that the increase in the total amount of specific IgG4 to an allergen extract (protein mixture) during immunotherapy gives no information about the increase of IgG4 to the patient's special major allergen.