The cells causing airway inflammation

Inflammation is the response of living tissue to injury and serves to restore the affected area to its original function. To a large extent the nature of the injury (e.g. micro-organisms, parasites, trauma or allergy) will determine the pattern of cell infiltration, as will the chronicity (the balance between the persistence of the insult and repair). Neutrophils and macrophages are the principal cells of acute inflammation, with eosinophils also participating in special circumstances, e.g. allergic and helminthic parasitic processes. In chronic inflammation, macrophages, lymphocytes and plasma cells are present in large numbers; again, the predominance of one cell type or other depends on the nature of the injury. Large numbers of basophils are also observed in certain delayed-in-time chronic processes but their role in lung pathology is uncertain. Similarly, platelets have potential for lung injury and their role in certain inflammatory states is established, although their participation in lung injury is still debated. The mast cell must also be considered since it is the repository for mediators which cause increased vascular permeability and has the potential for eliciting, and possibly sustaining, some of the white cell mediated events associated with the inflammatory process. Inflammatory cells cause injury by secretion of inflammatory mediators derived from their membranes (principally prostaglandins, leukotrienes and PAF-acether) and by elaboration of their granule constituents. Neutrophils have primary and secondary granules which contain an array of proteases and other enzymes, whereas eosinophils possess large amounts of unique basic proteins which have potential for direct cytotoxicity, i.e. of mucosal epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)