Pediatric Pulmonology 38:233–239 (2004) Lymphocytic Inflammation in Childhood

Summary. Childhood bronchiolitis obliterans (CBO) is an infrequent, severe disorder character-ized by persistent obstructive respiratory symptoms after an acute episode of bronchiolitis. The viral etiology is most common, and adenovirus is the most frequently identified causative agent. Pathologically, the disease is characterized as constrictive type BO, with variable degrees of chronic inflammation and fibrosis in the bronchioles. The nature of the cellular infiltrate is largely unknown, and its characterizationmay provide better understanding of the disease and offer clues for therapy.Therefore, theaimof thepresent studywas to characterize the inflammatory infiltrate in the bronchioles of 23 open lung biopsies of childrenwith CBOand to compare this to the infiltrate in histologically normal airways. Our results show that CD3þ T cells were themost frequent cell type observed inCBO,with a predominance of theCD8þT-cell subtype.When compared to the control group, there was a larger number of CD8þ, CD4þ, CD20þ, granzyme Bþ, and perforinþ lymphocytes in theCBOgroup.Further studiesareneeded to address the role of different cell type