The Role of the Cell Membrane in the Killing Mechanism of Polymorphonuclear Leucocytes (PMN)

Abstract

It is generally assumed that the killing of bacteria by leucocytes is performed exclusively intracellularly. However, the observation of a complement augmented cellular bactericidal mechanism raised doubts in that assumption (1). Complement activity is labile and transient and its intracellular action after phagocytosis therefore hard to imagine. Further studies revealed that the subsequent stages of phagocytosis were affected differently by complement activity. The attachment of bacteria to the cell membrane was particularly augmented but, surprisingly, the consecutive ingestion was not (2). This observation raised the question as to whether serum complement can act on the even later intracellular events, i.e. intracellular killing.