Abstract:

A heat-stable factor present in extracts of human blood leukocytes is capable of lysing young Staphylococcusaureusat pH 5.0. Lysis is character- ized by breakdown of cell-wall components as judged by electron microscopic and biochemical analysis. The leukocyte extracts can be replaced by a variety of agents known to injure cell membranes, e.g., leukocyte cationic protein histone, polymyxin B, colimycin, phospholipase A, and lysolecithin. The mechanisms by which all these agents bring about the degradation of the sta- phylococcal walls was studied. By using ~4C-labeled cell walls devoid of cytoplasmic structures, it was demonstrated that none of the above-men- tioned agents had a direct lytic effect on purified cell walls. On the other hand, when any of these agents first interacted with intact staphylococci, a factor (presumably an autolysin) was generated that directly lysed the cell walls. Lysis of cell wails in the presence of intact staphylococci used as a source of autolysin was strongly inhibited by a variety of anionic poly- electrolytes such as heparine and liquoid. The possible role olayed by bacterial autolysins in the generation of microbial cell-wall comp~,nents capable of triggering chronic inflammation is discussed.