Allergic Bronchopulmonary Aspergillosis (ABPA)
What is ABPA?Ā Allergic bronchopulmonary aspergillosis is a form ofĀ lung disease that occurs in some people who are allergicĀ to Aspergillus. With ABPA, this allergic reaction causesĀ the immune system to overreact to Aspergillus leadingĀ to lung infammation (This is why in the blood test, you'll find immunoglobulin E (IgE) level increased. This level is increasedĀ with any type of allergy. Many people with asthmaĀ have higher than normal IgE levels. In ABPA however, the IgE level is extremely high (more than 1000 ng/ ml or 417 IU/ml)) ABPA also causes bronchospasmĀ (tightening of airway muscles) and mucus buildupĀ resulting in coughing, breathing diffculty and airway obstruction.
A sputum culture (mucus coughed up from theairway) can be done to see if Aspergillus is growing in the airway but is not always reliable. Many people will have Aspergillus in their airway secretions (sputum) but not have ABPA. On the other hand, even if the culture is negative, a person can still have ABPA.
Chest X-rays are often not helpful in diagnosing ABPA. A CT scan (computed tomography) however, is a more detailed view of your lungs and therefore can be very helpful. The bronchiectasis is kind of a curve to the reader.
A blood test can be done to measure sepcifc IgE to Aspergillus. There are some other blood tests that also can help with the diagnosis
So basically, ABPA occurs in persons with asthma and those with cystic fibrosis (CF) but it's also possible for a normal person to have it. Aspergillus spores are small and can penetrate deep into the respiratory system to the alveolar level. In healthy people, innate and adaptive immune responses are triggered by various immune cells drawn to the site of infection by numerous inflammatory cytokines and neutrophilic attractants. In this situation, mucociliary clearance is initiated and spores are successfully phagocytosed, clearing the infection from the host. So if there's any condition that allowed Aspergillus spores to enter the lung & persist in pulmonary tissues, it permits successful germination which leads to hyphae growing in mucus plugs. From this, it will react to hypersinsitivity response, both a type I response (atopic, with formation of immunoglobulin E, or IgE) and a type III hypersensitivity response (with formation of immunoglobulin G, or IgG). The reaction of IgE with Aspergillus antigens results in mast cell degranulation with bronchoconstriction and increased capillary permeability. Immune complexes (a type III reaction) and inflammatory cells are deposited within the mucous membranes of the airways, leading to necrosis and eosinophilic infiltration.
A person with ABPA will have some or all of the following symptoms:
⢠Coughing frequently
⢠Coughing up mucus plugs that may be brown in color.
You may also cough up blood (hemoptysis).
⢠Diffculty exercising
⢠Wheezing
⢠Shortness of breath or feeling like it is difficult to get air into or out of your lungs.
⢠Chest pain or tightness
⢠Fever that goes away then comes back
⢠Fatigue
Source. American Academy of Allergy, Asthma & Immunology, American Thoracic Society, Medscape
So that's basically what's happening right now, but i still have a few question to ask, How is the mechanism of leukopenia in ABPA patient? Is it the same as in sepsis patient? (First, proinflammatory mediators work and then a compensatory anti-inflammatory response soon ensures that the effects of these proinflammatory mediators do not become destructive *which is why in the sepsis patient, most of them have leukocytosis in acute-phase and leukopenia in chronic phase)