ImmunoCAP Technology
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.
Agreement between systems
All Phadia systems are based on the same ImmunoCAP technology and can therefore be expected to show good agreement.
The agreement between Specific IgE in ImmunoCAP 100 and Pharmacia CAP System is excellent, as shown in Figure 2 (IR 12).
Figure 2. Comparison between ImmunoCAP 100 and Pharmacia CAP System.
The agreement between Specific IgE in ImmunoCAP 250 and Pharmacia CAP System is shown in Figure 3 (IR 13).
Figure 3. Comparison between ImmunoCAP 250 and Pharmacia CAP System.
Comparison studies between ImmunoCAP 1000 and ImmunoCAP 100 have been performed with 183 samples and 51 different allergens. Results for patient samples obtained with ImmunoCAP 1000 and ImmunoCAP 100 show good agreement, see Figure 4 (IR 14).
Figure 4. Comparison between ImmunoCAP 100 and ImmunoCAP 1000.
The agreement between ImmunoCAP 100 and ImmunoCAP 250 is also excellent, as shown in figure 5. The study consisted of 160 samples on 17 different allergens (IR 15).
Figure 5. Comparison between ImmunoCAP 100 and ImmunoCAP 250 (Data from van Campenhout, Antwerpen 2003).