The test is designed as a sandwich immunoassay. The unique part of the test system is the solid phase - ImmunoCAP. It consists of a cellulose derivative enclosed in a capsule. ImmunoCAP solid phase remains unrivalled as an optimal solid phase for allergy diagnostics. The hydrophilic, highly branched polymer provides an ideal microenvironment for allergens, binding them irreversibly while maintaining their native structure.
ImmunoCAP has an extremely high total binding capacity, achieved through a high binding capacity per mg cellulose in combination with an optimal amount of cellulose in each solid phase. This ensures binding of all relevant antibodies, regardless of antibody affinity, still giving low non-specific binding.
This provides high sensitivity and very low concentrations of IgE antibodies can be detected.
Figure 1. Binding capacity: plastic well, coated bed, paper disc and cellulose sponge.