MESSAGES AND HANDSHAKES - CELLULAR INTERACTIONS IN PULMONARY FIBROSIS

A better understanding of early cellular events following pulmonary in jury may permit the identification of those patterns of response which are destined to progress to fibrosis. Interactions between inflammato ry, fibroblastic and epithelial cells appear to play crucial roles in fibrogenesis. Intercellular communication may be via ''messages'' deli vered by soluble mediators or ''handshakes'' at sites of cell-to-cell contact. In this review, we question the validity of some prevailing c oncepts about the importance of growth factor secretion by alveolar ma crophages; examine the possible role of activated T-lymphocytes in reg ulating macrophage production of mediators; and hypothesise that where as fibroblast proliferation may primarily be stimulated by macrophage- derived cytokines, accumulation of collagen may be regulated by growth factors expressed by injured alveolar epithelial cells.