Measurement of Specific IgG Anti-Fel d 1 Antibodies

There is currently considerable interest in the role of specific IgG antibodies in allergy. Several studies suggest that specific IgG antibodies may play a protective role in allergy. Successful immunotherapy is associated with increases in allergen-specific IgG antibodies which correlate with clinical outcome. Other studies have identified an inverse relationship between exposure to cat and sensitization, which was associated with high titer specific IgG and IgG₄ . This immune response was described as a modified Th2 response, because both IgE and IgG₄ require Th2 cytokine IL-4 for their production. A modified Th2 response was described with laboratory animal allergy, where there was almost a twofold reduction in the risk of developing work-related chest symptoms.