Figure 2.

The functional valency of chimeric IgG4, plasma #178 and affinity-purified IgG4 from plasma #178. (a) Binding of ¹²⁵I-labelled Der p II to serial dilutions of chimeric IgG4 (17 μg/ml, •), plasma #178 (▵) and affinity purified IgG4 from plasma #178 (○) to Sepharose-coupled Staphylococcal Protein A were tested and used to determine the amount of Der p II-specific IgG₁₂₄ in the plasma. (b) The cross-linking of Sepharose-coupled mite-extract to ¹²⁵I-labelled Der p II by chimeric IgG4 (•), plasma #178 (▵) or affinity-purified IgG4 from plasma #178 (○) was expressed as the amount of radioactivity bound relative to the amount of radioactivity added.