The extracellular stimulation of intracellular killing by phagocytes.

Abstract

Phagocytes, granulocytes, and mononuclear phagocytes are the major effector cells in the host defence against invading micro-organisms, which these cells ingest, kill intracellularly, and digest. It has been known since the beginning of the century that serum proteins called opsonins are obligatory for optimal ingestion of microorganisms by phagocytes1–4. However, the effect of not only these opsonic but also other serum proteins on the other stages of the phagocytic process, and in particular killing and digestion is less clear. This is due mainly to the fact that until recently it was almost impossible to assess intracellular killing from the continuous ingestion of new live bacteria affecting this measurement5–7. In the present study we used a recently developed method,8,9 to investigate the effect of extracellular stimuli, serum proteins as well as membrane pertubating agents, on the intracellular killing of micro-organisms by granulocytes and monocytes.