A 30-year-old male is having difficulty breathing and has been spitting blood. He reports that he began experiencing this reaction after cleaning his pigeons’ cages. Testing reveals he is suffering from allergic alveolitis. Which of the following is he experiencing?

The normal host defense mechanisms against infection include (1) normal skin and mucous membranes, (2) phagocytic system, (3) humoral immunity, and (4) cellular immunity. The compromised host is an individual who has one or more defects in these defense mechanisms. (Source: NIH.gov)