Cytokinetics of mononuclear phagocyte response to listeriosis in genetically-determined sensitive and resistant murine hosts.

Genetically-determined differences in resistance to infection with L. monocytogenes are controlled by a single, non-H-2 linked gene Lr, which is expressed in some facet of the response of the mononuclear phagocyte system to listeriosis. In this study, the kinetics of monocyte production and turnover have been compared in Listeria-resistant B10.A and Listeria-sensitive A strain mice, in response to either listerial infection or stimulation with a water-soluble monocytosis-producing activity extracted from L. monocytogenes. Promonocyte generation time in resistant mice fell from approximately 17 to 13 h on the first day of infection, or several hours following injection of monocytosis-producing activity, whereas there was no such shortening of promonocyte generation time in susceptible mice at these times. Similarly, the half-time of circulating monocytes fell by approximately 8-9 h following listerial infection or injection of extracts of monocytosis-producing activity in resistant, but not in susceptible, mice. The Lr gene may, therefore, be controlling the production and emigration of mononuclear phagocytes shortly following infection, this in turn determining the degree of susceptibility of the host to listeriosis.