Transforming factor β₁ (TGF‐β₁) genetic polymorphisms have been identified as a modifier of cystic fibrosis (CF) lung disease severity. However, few data link TGF‐β₁ protein levels and clinical markers of CF lung disease severity.

To determine the association between protein levels of TGF‐β₁ in pediatric CF bronchoalveolar lavage fluid (BALF) and clinical parameters of CF lung disease severity.

Total TGF‐β₁ was measured in BALF from 30 pediatric CF patients and 12 non‐CF disease controls undergoing clinically indicated flexible bronchoscopy, and compared to four indicators of clinical disease: infection, inflammation, pulmonary function, and recent/recurrent hospitalization.

TGF‐β₁ was elevated in CF BALF compared to non‐CF controls (135 ± 15 pg/ml vs. 57 ± 10 pg/ml, P < 0.01). In CF BALF, increased TGF‐β₁ was associated with elevated BALF PMN % (r = 0.67, P < 0.01). BALF TGF‐β₁ was increased in CF subjects whose FEV₁ after the completion of antibiotic therapy remained below CF age‐normative median values (205.9 ± 20.5 pg/ml vs. 106.4 ± 24.0, P = 0.01). BALF TGF‐β₁ was increased in CF children hospitalized in the previous year compared to those not recently hospitalized (169.9 ± 21.6 pg/ml vs. 107.5 ± 17.5 pg/ml, P = 0.04). Neither the presence of a bacterial pathogen nor bacterial quantity was associated with BALF TGF‐β₁.

In CF, BALF TGF‐β₁ is elevated compared to non‐CF controls. Increased BALF TGF‐β₁ is associated with neutrophilic inflammation, diminished lung function and recent hospitalization. Further investigation is needed to address mechanisms behind these associations. Pediatr Pulmonol. 2009; 44:1057–1064. ©2009 Wiley‐Liss, Inc.