In vitro studies on the interaction between mouse peritoneal macrophages and strains of Salmonella and Escherichia coli

On the participation of antibodies and complement in the antibacterial activity of an extract from rabbit polymorphonuclear leucocytes

Antibacterial activity against Escherichia coli was found in the cytoplasmic extracts of rabbit polymorphonuclear leucocytes. The lack of antibody activity was determined by agglutination, passive haemagglutination, bactericidal reaction in the presence of complement, bactericidal plaque technique and immunoelectrophoresis. Thermostability of the extract, higher activity in a sodium citrate buffer than in veronal buffer containing Ca^{+ +} and Mg^{+ +} and negative haemolysis give evidence against the participation of complement in this type of antibacterial activity. Inhibition of the activity following absorption with different bacterial suspensions is interpreted as involving electrostatic bonds between active cationic substances and the negative charge of the bacterial surfaces. In addition, inhibition of the antibacterial activity was proved in the presence of both native and inactivated piglet and rabbit whole sera and albumin, which suggests that there is no independent action of these cytoplasmic substances in serum in vivo.

Raffel S, Ferraresi RW: Delayed hypersensitivity in relation to suppression of growth of Listeria monocytogenes by guinea pig macrophages

Prototypes of delayed hypersensitivity (tuberculin allergy, graft rejection immunity, and contact dermatitis) were established in guinea pigs. The macrophages from peritoneal exudates of such animals were examined for their capacities to suppress the growth of Listeria monocytogenes in vitro. Only the macrophages from animals sensitized to BCG clearly exhibited this property.

Effect of specific immune mouse serum on the growth of Salmonella enteritidis in mice preimmunized with living or ethyl alcohol-killed vaccines

The effect of prior opsonization of virulent Salmonella enteritidis on the growth of this organism in blood, liver, spleen, peritoneal cavity, and inguinal lymph node of specific pathogen-free mice prevaccinated with ethyl alcohol-killed S. enteritidis or living S. gallinarum was determined by daily enumeration. Both the vaccines and the challenge inocula were injected by the intravenous, intraperitoneal, or subcutaneous routes to determine the effect of variations in the vaccinating procedure on the level of immunity induced. The survival percentage observed in mice vaccinated with killed organisms varied extensively, depending on the route of challenge. However, simultaneous organ enumeration studies revealed that vaccination with killed organisms failed to prevent the growth of the challenge organism in vivo. On the other hand, virulent S. enteritidis injected into mice vaccinated with living S: gallinarum failed to multiply and was subsequently eliminated. Immunity in these animals was so effective that a subcutaneously injected challenge did not spread beyond the regional node. Immunization with killed organisms slowed but was unable to prevent the spread of such a challenge beyond the draining node involved in the primary immune response. Neither the route of challenge nor the regimen used in the vaccination had any appreciable influence on the level of antibacterial immunity detected in the organs of the reticuloendothelial system at the time of challenge.

Interactions between macrophages of guinea pigs and Salmonellae. I. Fate of Salmonella typhimurium within macrophages of normal guinea pigs

A suspended cell culture procedure was described for the cultivation of guinea pig macrophages infected with Salmonella typhimurium. The fate of the intracellular bacteria was assessed by quantitative recovery of viable bacteria with 0.5% solution of sodium desoxycholate. Two strains of S. typhimurium with different degrees of virulence for mice were compared. There was an initial destruction of intracellular bacteria of both strains; however, the extent of this destruction differed. Approximately 1% of the avirulent bacteria initially phagocytized survived at the end of 4 hr, whereas approximately 8% of the virulent bacteria survived at the end of 3 hr. After this initial killing, the intracellular bacteria began to multiply at a logarithmic rate between 3 and 21 hr after phagocytosis, and then a stationary phase was attained. The rate of this multiplication was comparable for both strains.

Serum-mediated immune cellular responses to Brucella melitensis. I. Role of a macrophage-stimulating factor in promoting ingestion of Brucella by streptomycin-protected cells

Injection of rabbits with living Brucella melitensis Rev I induced the appearance of a macrophage-stimulating-factor (MSF) in the sera of these animals. MSF was involved in ingestion of bacilli, hastening the formation of protected loci as measured by the addition of lethal amounts of dihydrostreptomycin. When sufficient time had been allowed for effective ingestion, streptomycin had little effect. This in turn allowed for multiplication of bacilli intracellularly in the presence of 5 to 250 mug of drug per ml. MSF mediated more effective ingestion by both immune and normal macrophages. Under such conditions, there was little, if any, intracellular growth restriction by macrophages from immune animals. The activity appeared within the first 5 days after injection with 10(9) organisms and was present for several months. Three weeks after injection, the activity of serum was partially heat-labile. All activity was removed by absorption with heat-killed or living Rev I cells, suggesting that a specific globulin is concerned.

Cellular hypersensitivity and cellular immunity in the pathogensis of tuberculosis: specificity, systemic and local nature, and associated macrophage enzymes

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Autoradiographic evidence for the impermeability of mouse peritoneal macrophages to tritiated streptomycin

Cultured mouse peritoneal macrophages were found to be relatively impermeable to streptomycin. Based on radioactivity measurements and radioautographic evidence, macrophages were impermeable to tritiated dihydrostreptomycin for periods up to 20 hr of incubation. Little or no intracellular streptomycin could be detected even when incubation was carried out in the presence of therapeutic blood levels of carrier dihydrostreptomycin. When the cultured mouse macrophages were allowed to phagocytize staphylococci, yeast cells, or polystyrene latex particles in the presence of tritiated streptomycin, the impermeability of the cells to the antibiotic was not affected. These observations suggested that the process of phagocytosis does not facilitate the intracellular accumulation of streptomycin, as seems to be the case for the fixed phagocytic cells of the liver.

Mechanisms of acquired resistance in mouse typhoid

Experiments in vitro comparing normal mouse peritoneal macrophages with cells from Salmonella typhimurium-infected mice have shown that the "immune" macrophages have conspicuously enhanced microbicidal properties. Whereas normal macrophages could inactivate only 50 to 60% of intracellular S. typhimurium pretreated with immune serum, cells from infected animals killed virtually all ingested organisms and did so at an accelerated rate. Macrophages from Listeria monocytogenes-infected mice were shown to possess similarly enhanced microbicidal activity against S. typhimurium. Furthermore, the growth of S. typhimurium in the liver and spleen was more effectively restricted in Listeria-infected mice than in animals vaccinated with heat-killed S. typhimurium, even though the Listeria-infected animals possessed no demonstrable cross-reacting antibody to S. typhimurium. The lack of resistance in the mice vaccinated with heat-killed organisms could not be attributed to any deficiency of humoral factors, since the serum from these animals was as effective at promoting phagocytosis and killing by macrophages as serum from actively infected (and demonstrably resistant) mice. Conversely, Salmonella-infected mice were totally resistant to intravenous challenge with L. monocytogenes. The level of resistance in individual animals was related to the numbers of residual Salmonellae remaining in the tissues; mice with heavier residual infections being the more resistant. Specific antiserum from mice vaccinated with heat-killed S. typhimurium was found to be significantly protective only when the intraperitoneal route of challenge was employed. The foregoing studies have been interpreted to mean that enhancement of the microbicidal ability of macrophages is the mechanism of major importance in acquired resistance to S. typhimurium infection in mice.

Intracellular production of Brucella L forms . II. Induction and survival of Brucella abortus L forms in tissue culture

Hatten, Betty A. (The University of Texas Southwestern Medical School, Dallas), and S. Edward Sulkin. Intracellular production of Brucella L forms. II. Induction and survival of Brucella abortus L forms in tissue culture. J. Bacteriol. 91:14-20. 1966.-Intracellular survival of altered brucellae, possibly L forms, was not greatly affected by penicillin or streptomycin in concentrations ranging from 5.0 to 40 mug/ml, but a combination of these two antibiotics (2.5 to 20 mug/ml each) reduced the number of positive L-form cultures. Tetracycline (2.0 mug/ml) decreased the number of positive L-form cultures at about the same rate as combinations of the higher concentrations of penicillin and streptomycin. Various concentrations of tetracycline (0.1 to 2.0 mug/ml) with 5.0 mug/ml of penicillin or streptomycin significantly reduced the number of positive L-form cultures. L forms were recovered for several days after elimination of bacteria from the cultures by all of the antibiotics tested. L-form production was not dependent upon the presence of antibiotics in the culture medium, but they were recovered in greater numbers when bacteria were still present in the hamster kidney cells. Addition of thallium acetate to infected cells (at varying intervals of time after infection) to control bacterial growth and conversion to the L phase during cellular disintegration decreased the number of positive L-form cultures obtained over a 10-day period. Comparison of the antibiotic sensitivity of bacteria recovered from infected tissue culture cells with the stock strain of Brucella abortus indicated that some resistance to penicillin and tetracycline had developed. A marked resistance to streptomycin was observed in those bacteria recovered from cells maintained in the presence of this antibiotic.

FACTORS INFLUENCING THE PHAGOCYTOSIS OF ESCHERICHIA COLI

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EFFECT OF A RETICULOENDOTHELIAL STIMULATING AGENT (RESTIM) ON RESISTANCE OF MICE

Ransom, John P. (New England Institute for Medical Research, Ridgefield, Conn.), Varsenig Z. Pasternak, and John H. Heller . Effect of a reticuloendothelial stimulating agent (restim) on resistance of mice. J. Bacteriol. 84: 466–472. 1962.—The effect of restim, a preparation of yeast cell walls, on resistance of mice to challenge by Salmonella typhimurium has been investigated. Although restim markedly increases the rate of phagocytosis and clearance of carbon particles, and presumably of viable bacterial cells, this activity has no significant effect on the course of events when restim-treated mice are challenged with S. typhimurium . However, when specific antibody derived from either active or passive immunization of the mice is present, restim significantly enhances resistance as judged by survival time and by 20-day survival.

Hyperreactivity to endotoxin in mice infected with mycobacteria. Induction and elicitation of the reactions

In the mouse, the parenteral injection of whole mycobacteria, cord factor or mycobacterial cell walls induces a 100 to 500,000 fold decrease in the acute i/v LD₅₀ of endotoxic lipopolysaccharide (LPS) of Gram-negative organisms.

Non-specific hyperreactivity of this kind is more easily induced by infection with living mycobacteria than by injection of dead organisms, and more easily when these are injected intravenously than intraperitoneally; but BCG and other strains of low virulence are as effective as fully virulent strains such as H₃₇R_v or Vallée.

The hyperreactivity reaches a maximum at 7–9 days and persists for at least 3 weeks. All of four strains of mice tested behaved similarly.

Intracellular killing of Micrococcus lysodeikticus by macrophages and polymorphonuclear leucocytes: a comparative study

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