[Biology and clinical aspects of intracellular resistance to infection].

Normal functioning of phagocytic cells depends upon the integration of chemotaxis, phagocytosis, degranulation and oxidative metabolism. The availability of in vitro assays for the separate quantitative evaluation of each function has permitted the definition of specific congenital and acquired abnormalities of phagocytic cells which are associated with defective mechanisms of host resistance. The appreciation of complex and often adverse effects of certain systemic diseases and pharmacological agents on the phagocytes, as well as the use of new approaches to therapy underline the importance of assessing the role of phagocytic cells in states of impaired host defence. In addition, cellular immune mechanisms involving the interaction of T-cells and macrophages contribute essentially to the proper functioning of intracellular host defence, as indicated by the delayed type hypersensitivity reaction.