CELL-INTERACTIONS OF LISTERIA-MONOCYTOGENES L FORMS AND PERITONEAL EXUDATIVE CELLS RATS

Listeria monocytogenes 4b and its forms without cell walls (L forms of a protoplastic type) were used to study in vivo interactions with hos t cells. Samples of peritoneal lavage fluid were obtained from rats in traperitoneally inoculated at intervals between 1 and 15 days after ch allenge, for scanning electron microscopic, bacteriological, biochemic al, and cytometrical investigations. Scanning electron microscopic exa mination revealed continuous adhesion of L forms on the macrophage sur face up to 15 days after inoculation, The persistence of the L forms w ithin the peritoneal cavity was also shown bacteriologically at all sa mple times, while the parental bacterial forms were isolated from the peritoneal cavity up to 7 days after challenge. The total count of per itoneal exudative cells determined by automated flow peroxidase cytome try peaked on the 15th day in animals infected with parental forms, wh ile in animals infected with L forms the peak was lower and the macrop hage population was predominant. The glycolytic and acid phosphatase a ctivity of peritoneal exudative cells was two times higher in rats inf ected with L forms as compared with rats infected with the L. monocyto genes parental forms on the 3rd day after challenge. An understanding of the nature of the interactions between L forms of L. monocytogenes and peritoneal exudative cells found in vivo could be used to establis h the influence of L forms on host cellular defense mechanisms.