ANTIBIOTIC PROTEINS OF POLYMORPHONUCLEAR LEUKOCYTES

The polymorphonuclear leukocyte (PMN) plays an essential role in the i nnate defense of the mammalian host against bacterial invaders. Respon ding chemotactically, the PMN delivers a complex antibiotic arsenal to sites of infection. Among these cytotoxic systems is an array of anti microbial proteins and peptides that the PMN directs at microorganisms both before (i.e. extracellularly) and after sequestration into a pha gocytic vacuole. In addition to their microbicidal capacity, several o f these proteins bind to and neutralize the endotoxic activity of Gram -negative bacterial lipopolysaccharides (LPS). In this review the prin ciple features of these antibiotic proteins are briefly summarized wit h emphasis on their possible actions in biological settings. In many i nstances, additional functions independent of cytotoxicity have been d escribed raising the possibility that some of these proteins subserve multiple roles in inflammation.