T cells and eosinophils in asthma.

The bronchial inflammation characterising asthma represents a specialised form of cell-mediated immune reactions, in which products of activated CD4+ T cells orchestrate the accumulation and activation of granulocytes, particularly eosinophils. Through their toxic granule proteins, membrane derived lipid mediators and proinflammatory cytokines, eosinophils are suggested to be responsible for the changes in airway submucosal tissue resulting in altered airway responsiveness. T cell activation is followed by the synthesis and release of cytokines of which IL-3, IL-5 and GM-CSF are particularly important in the site-specific accumulation, prolonged survival and activation of eosinophils. This review focuses on the interaction of these two cell types with particular interest in the cytokines which may be responsible for the development of eosinophilic airway inflammation.