Since BAL is by far a less invasive technique than tissue biopsy to study pathogenetic mechanisms in IPF we further evaluated the usefulness offered by this means studying the relationship between BAL macrophages, neutrophils, eosinophils, CD3+, CD4+, CD8+, CD8+/38+ TLs and CD4+/CD8+ ratio with breathlessness and physiological indices, in IPF patients. Here, CD4 is linked to idiopathic pulmonary fibrosis.