Antibody isotype responses in Aspergillus-induced diseases

Area of Science:

• Immunology
• Medical Mycology
• Clinical Diagnostics

Background:

• Allergic bronchopulmonary aspergillosis (ABPA) and aspergilloma are conditions associated with Aspergillus fumigatus sensitization.
• Understanding the specific immunoglobulin response is crucial for diagnosis and management.

Purpose of the Study:

• To evaluate and compare Aspergillus fumigatus-specific immunoglobulin (Ig) classes and subclasses in patients with ABPA, aspergilloma, and asthma.
• To differentiate immune responses in various Aspergillus-related conditions.

Main Methods:

• Sera from patients with ABPA, aspergilloma, Aspergillus-reactive asthma, and healthy controls were analyzed.
• A sensitive sandwich enzyme immunoassay with biotin-avidin amplification was employed to detect specific antibodies.

Main Results:

• No significant differences in most specific antibody levels were found between healthy controls and Aspergillus-reactive asthmatics, except for IgD and IgG4.
• Allergic bronchopulmonary aspergillosis (ABPA) sera exhibited significantly elevated levels of all A. fumigatus-specific Ig isotypes.
• Aspergilloma sera showed increased IgA, IgG1, IgG2, and IgG3 compared to asthmatic individuals.
• In ABPA, IgG1 and IgG2 subclasses were elevated (60% IgG2, 40% IgG1), while IgG1 predominated in aspergilloma.
• Newly diagnosed ABPA patients had considerably higher specific Ig isotypes compared to treated or asymptomatic patients.

Conclusions:

• Aspergillus fumigatus-specific antibody profiling, particularly Ig isotypes and IgG subclasses, can help differentiate between ABPA and aspergilloma.
• Elevated Ig levels in ABPA are indicative of active disease and are significantly higher than in treated or asymptomatic individuals.