"Aspergillus terreus" causes opportunistic infections mostly in immunocompromised people such as COPD patients who are taking corticosteroids, cancer patients receiving chemotherapy treatment, or HIV/AIDS patients. In an immunocompetent individual, the inhalation of spores initiates an immediate release of macrophages and neutrophils. In an immunosuppressed individual, this response is less vigorous. Most of these individuals suffer from neutropenia, which makes them less capable of defending themselves. In addition, "A. terreus" releases toxic metabolites that attack immune cells like neutrophils which provide the suitable conditions for the fungus to thrive.