Kinetics of killing Listeria monocytogenes by macrophages: rapid killing accompanying phagocytosis
The kinetics of bactericidal activity of activated macrophages can be precisely described by a mathematical model in which phagocytosis, killing, digestion, and release of degraded bacterial material are considered to occur continuously. To gain a better understanding of these events, I have determined the period of time between first contact of bacteria with macrophages and the onset of killing. Activated rat peritoneal macrophages were incubated for various times up to 15 min with Listeria monocytogenes previously labeled with /sup 3/H-thymidine and the unassociated bacteria removed by two centrifugations through a density interface. Both cell-associated radioactivity and cell-associated viable bacteria, determined as colony forming units after sonication of the cell pellet, increased with time of incubation. However, the specific viability of these bacteria, expressed as the ratio of number of viable bacteria per unit radioactivity declined with time, as an approximate inverse exponential, after a lag period of 2.9 +/- 0.8 min. Evidence is given that other possible causes for this decline in specific viability, other than death of the bacteria, such as preferential ingestion of dead Listeria, clumping of bacteria, variations in autolytic activity, or release of Listericidins are unlikely. I conclude therefore that activated macrophages kill Listeria approximately 3 min after the cell and the bacterium first make contact.
- Research Organization:
- Kolling Institute of Medical Research, Royal North Shore Hospital of Sydney, St. Leonards, N.S.W., Australia
- OSTI ID:
- 5653452
- Journal Information:
- J. Reticuloendothel. Soc.; (United States), Vol. 34:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BACTERIA
PHAGOCYTOSIS
KINETICS
CELL KILLING
CENTRIFUGATION
MACROPHAGES
MATHEMATICAL MODELS
THYMINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMAL CELLS
AZINES
CONNECTIVE TISSUE CELLS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MICROORGANISMS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHAGOCYTES
PYRIMIDINES
SEPARATION PROCESSES
SOMATIC CELLS
URACILS
551001* - Physiological Systems- Tracer Techniques