Specificity of IgE-binding to sugar beet pollen proteins and Che a 2. Preincubation of the serum was performed to test whether the IgE-binding could be inhibited by purified recombinant Chenopodium allergens. Serum from individual 15, with high levels of specific IgE (Table 1) was used (lanes 1–3, 5–8, 10), and 17 = negative control (lane 4, 9, 11). A. Serum to be used as primary antibody was preincubated with recombinant allergens Che a 1 (lane 1), Che a 2 (lane 2), Che a 3 (lane 3). B. Serum to be used as primary antibody was preincubated with recombinant allergen Che a 2 (lanes 6 and 8), and using two different secondary antibodies, one polyclonal (lanes 5, 6, also used in lanes 1–3) and one monoclonal two-step antibody (lanes 7, 8, 9). Immunoblotting of SDS-PAGE with sugar beet pollen extract in A. and B. C. Immunoblotting of SDS-PAGE with recombinant Che a 2 subjected to SDS-PAGE, serum from individual 15 (lane 10) and 17 = negative control (lane 11).