PULMONARY IMMUNE CELLS IN HEALTH AND DISEASE - THE EOSINOPHIL LEUKOCYTE .1.

Increasing evidence has accumulated to suggest that eosinophils play a key role in the pathogenesis of asthma and other pulmonary diseases b y damaging infiltrated bronchial tissue and lung parenchyma. The first part of this review on eosinophils describes the cellular characteris tics and properties of the cell, which help in understanding its role in disease. The article focuses on origin, maturation and differentiat ion of the eosinophil, its morphological and phenotypical properties, as well as its preformed and newly generated mediators of inflammation . The cause and putative significance of eosinophil heterogeneity in r espect to function and density will also be discussed. In addition, th e naturally occurring mediators through which eosinophils are activate d and communicate with other inflammatory cells are outlined. The firs t part closes with new aspects of eosinophil recruitment from the circ ulation into perivascular tissue, including nonselective and putative selective adhesion mechanisms and chemotaxis.