What type of infiltration is predominantly seen in cystic fibrosis lung biopsies?

In cystic fibrosis, the lungs are heavily affected by chronic infection and inflammation, primarily due to the accumulation of thick mucus that obstructs airways and provides a favorable environment for bacterial growth. The predominant type of infiltration seen in lung biopsies of individuals with cystic fibrosis is neutrophilic infiltration.

This neutrophilic response is a direct consequence of continuous bacterial colonization and recurrent infections, notably with organisms such as Pseudomonas aeruginosa. Neutrophils react to these infections with an inflammatory response intended to eliminate the pathogens. However, in cystic fibrosis, due to the persistent nature of infections and the impaired mucociliary clearance, neutrophils can accumulate in high numbers, leading to further lung damage rather than effective resolution of the infection.

In contrast, other types of infiltration, such as lymphocytic or eosinophilic, are typically associated with different pathologies, including viral infections or allergic responses, respectively. Plasmacytic infiltration is linked to chronic antigenic stimulation or immune responses, but it is not characteristic of cystic fibrosis lung pathology. Thus, the significant neutrophilic infiltration in the context of cystic fibrosis lung biopsies reflects the body's response to chronic infection and tissue damage.