Immune effector cells in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a poorly understood immunomediated disorder that is characterized by three major features; influx of inflammatory cells into the lower respiratory tract, alveolar epithelial or capillary cell injury, and release of cytokines that stimulate proliferation of fibroblasts and type II pneumocytes along with deposition of extracellular matrix proteins, notably collagen. In the past few years interest in the pathogenetic mechanisms taking place in IPF has focused on immune effector cells that are involved in pulmonary inflammatory pathways, cell-specific injury, and fibroblast activation. In particular, accumulating evidence indicates that a complex relationship exists between the macrophage/lymphocyte/neutrophil cellular axis and the local network of cytokines that, through paracrine and autocrine interactions, coordinate inflammation and fibrogenesis in the respiratory tract.