In Vitro Interactions Between Rabbit Alveolar Macrophages andPasteurella tularensis

Abstract

In vitro interactions between rabbit alveolar macrophages and Pasteurella tularensis. J. Bacteriol. 92:645-651. 1966.-Rabbit alveolar macrophages were successfully employed in a study of host cell-Pasteurella tularensis interactions in vitro. Under cell culture conditions in which inhibitory antibiotics were not employed and small infection ratios were used, the relative in vivo virulence of two strains of P. tularensis was duplicated. As a consequence of intracellular multiplication, normal macrophages were killed in relation to the virulence of the strain employed. Alveolar macrophages were also collected from une rabbits, and macrophage mortality and bacterial growth were significantly suppressed below levels observed with normal macrophage preparations. The effect of iune serum could only be ascribed a minor role in the observed reactions. A marked intravenous toxicity of P. tularensis for the rabbit was observed with both virulent and attenuated strains. The toxicity was possessed only by viable preparations and could be elicited in animals immune to virulent challenge.

Phagocytosis of Francisella tularensis by Rhesus monkey peripheral leukocytes

“…coli or latex particles, whereas in the presence of LVS and normal serum, extracellular enzyme activity was the same as that of PMN control mixtures. In the presence of LVS and immune serum, however, lysosomal enzyme release was DISCUSSION In view of the abundant evidence that specific immune opsonin is not required for phagocytosis of F. tularensis by fixed or migrating MN phagocytes from many animal species (5,10,12,17,21), a finding confirmed in the present study with oil-induced monkey peritoneal macrophages, the specific antibody requirement for F. tularensis activation of oxidative metabolism and lysosomal enzyme release by monkey PMN was unexpected. Although it is conceivable that F. tularensis can infect PMN without significant biochemical activation of the phagocyte and, by ablating degranulation, facilitate its intracellular survival, our autoradiographic and electron microscopic evidence argues against such a possibility.…”

“…Complex enzymatic and metabolic interactions between bacteria and phagocytic cells are required for efficient phagocytosis and killing of microorganisms (8,9). However, certain bacteria such as Francisella tularensis can mitigate the normal functions of host defense mechanisms, evade phagocytosis, proliferate within certain cells, and caused extensive damage (5,12).…”

Stimulation of Subpopulations of Human Lymphocytes by a Vaccine Strain of Francisella tularensis

“…Furthermore, antibodies have not affected the survival ofF. tularensis in in vitro experiments, whereas mononuclear cells from specifically immunized animals have killed the bacteria efficiently (21,29). The present results suggest that the lymphocyte stimulation test estimated mainly T-lymphocyte reactivity when membranes or whole bacteria of F. tularensis are used as antigen.…”

“…In both these situations, a cellular as well as a humoral immunity develops in the host. The cellular immunity seems to be more important to the resistance than humoral antibodies (1,6,21,30). Thus, specific protection against tularemia can be conferred by passive transfer of thoracic duct lymphocytes from immunized to nonimmunized rats (18).…”

Stimulation of human lymphocytes by a vaccine strain of Francisella tularensis

“…Francisella tularensis induces into various mammals a cell-mediated immune response which is probably more important for resistance against infection than is the presence of serum antibodies (1,4,16,22,27). In man, delayed cutaneous hypersensitivity can be elicited after infection or vaccination by F. tularensis (3,8).…”