Background: Recently it was shown that in Idiopathic Pulmonary Fibrosis (IPF) tissue infiltrating CD8+ T lymphocytes (TLs) are associated with breathlessness and physiological indices of disease severity, as well as that CD8+ TLs recovered by bronchoalveolar lavage (BAL) relate to those infiltrating lung tissue. Since BAL is a far less invasive technique than tissue biopsy to study mechanisms in IPF we further investigated the usefulness offered by this means by studying the relationship between BAL macrophages, neutrophils, eosinophils, CD3+, CD4+, CD8+, CD8+/38+ TLs and CD4+/CD8+ ratio with breathlessness and physiological indices.
Patients and methods: 27 IPF patients, 63 +/- 9 years of age were examined. Cell counts were expressed as percentages of total cells and TLs were evaluated by flow cytometry. FEV1, FVC, TLC, RV, DLCO, PaO2, and PaCO2 were measured in all. Breathlessness was assessed by the Medical Research Council (MRC) chronic dyspnoea scale.
Results: CD8+ TLs correlated positively (rs = 0.46, p = 0.02), while CD4+/CD8+ ratio negatively (rs = -0.54, p = 0.006) with the MRC grade. CD8+ TLs correlated negatively with RV (rs = -0.50, p = 0.017). CD8+/38+ TLs were negatively related to the FEV1 and FVC (rs = -0.53, p = 0.03 and rs = -0.59, p = 0.02, respectively). Neutrophils correlated positively with the MRC grade (rs = 0.42, p = 0.03), and negatively with the DLCO (rs = -0.54, p = 0.005), PaO2 (rs = -0.44, p = 0.03), and PaCO2 (rs = -0.52, p = 0.01).
Conclusion: BAL CD8+ TLs associations with physiological and clinical indices seem to indicate their implication in IPF pathogenesis, confirming our previous tissue study.