Tubercle bacilli of the pathogenic human strain H37Rv had previously been shown to multiply, after ingestion by cultured mouse peritoneal macrophages, within phagosomes that tended to remain unfused with secondary lysosomes. Means were sought therefore for promoting experimentally a modification of the host response so as to attain a high level of phagolysosome formation, enabling tests to be made of any effects on the course and outcome of the intracellular infection. This was achieved by exposing viable bacilli to specific rabbit antiserum before their ingestion. Quantitative assessments, using electron microscopy, now showed that a majority of the phagosomes containing intact bacilli had fused with ferritin-labeled lysosomes, and frequently the fusion was massive. Bacterial viability studies established that the serum pretreatment was not itsel bactericidal. In the course of progressive infections with strain H37Rv, monitored by counts both of viable bacterial units and of intracellular acid-fast organisms, no appreciable difference was found between the intracellular growth rates of control and antiserum-treated bacilli. Concurrent electron microscopy showed that bacilli could remain intact and multiply both in phaagolysosomes and in unfused phagosomes, ruling out the possibility of selective growth of antiserum-pretreated bacilli within the minority of phagosomes that remained unfused. It was concluded that "turning on" phagosome-lysosome fusion in normal macrophages did not influence the outcome of infection with virulent M. tuberculosis; lysosome contents manifestly failed to exercise an antibacterial effect on this organism. Nevertheless, the possibility remains that the lysosomes of specific immune macrophages have antituberculous potentiality. In that case the experimental "turning on or off" of fusion could be a decisive factor in the outcome of a virulent challenge. Should it not be, the antibacterial capabilities of immune cells would need to be ascribed to factors other than lysosomal attack, the latter being essentially for disposal of the dead organisms.

https://rupress.org/jem/article-pdf/142/1/1/1267442/1.pdf

Phagosome-lysosome interactions in cultured macrophages infected with virulent tubercle bacilli. Reversal of the usual nonfusion pattern and observations on bacterial survival.

The authors argue that plague should be taken much more seriously by the international health community.

/pdf/plague-past-present-and-future-4yvkf2520n.pdf

Plague: past, present, and future.

A. Macrophage-Dependent Resistance in the Absence of Specific Immune Responses.... 1223 B. Augmentation of Macrophage Numbers by Local Proliferation and Influx of Monocytes from the Blood 1223 C. Granuloma Formation 1224 D. Macrophage Activation 1224 E. The Genetic Basis of Mononuclear Phagocyte-Dependent Resistance ......... 1226 F. Role of Polymorphonuclear Leukocytes .... 1226

The Role of Cell-Mediated Immunity in Bacterial Infections

Brucellosis vaccines: past, present and future.

(1973). Bacterial Assimilation of iron. CRC Critical Reviews in Microbiology: Vol. 2, No. 3, pp. 273-331.

Bacterial Assimilation of iron

Resistance to infection with Yersinia pestis was found to depend on whether the macrophage can inactivate and withstand the cytotoxic effects of phagocytized Y. pestis. Serum from mice immunized with antigens of Y. pestis enhanced the resistance of monolayers of normal cultures to the cytotoxic effects of Y. pestis and increased the capacity of peritoneal exudate cells from immune mice to inactivate these bacteria. The enhancing component of the serum was not removed by absorption with heat-killed Y. pestis. Similar enhancement was provided by supernatant fluids of spleen cultures from immunized mice but not by those from unimmunized mice. Pretreatment of spleen cells with rabbit hyperimmune antiserum to mouse brain theta-antigen plus complement caused a reduction in the enhancing capacity of the spleen cell culture fluids. Removal of the glass-adherent cell population from suspensions of primed spleen cells prior to in vitro antigenic stimulation resulted in a loss of activity from the subsequently harvested culture fluids. Thus, the enhancing component of the serum appears to be a product of thymus-derived lymphocytes (T-cells). Furthermore, splenic macrophages seem to be required for the interaction of primed T-cells with heat-killed Y. pestis.

Cellular Immune Response to Yersinia pestis Modulated by Product (s) from Thymus-Derived Lymphocytes

ConclusionStudies on mononuclear cell responses to B. melitensis require that attention be paid especially to the nature of inflammatory agent itself when interpreting behavior of the mononuclear cell. The inflammatory substance may so alter mononuclear response as to reverse cytolytic susceptibility of monocytes from normal and immunized animals.

Response of Peritoneal Exudate Cells to Brucella melitensis. Influence of Nature of Inflammatory Irritant.

Protection against pneumonic plague by the oral administration of a live, attenuated Yersinia pestis vaccine, EV76 (Paris) F, was evaluated in the vervet (Cercopithecus aethips). Six animals were vaccinated with a dose of 1.175 X 10(9) colony-forming units (cfu); all tolerated the dose and developed antibodies to Fraction I of Y. pestis. Three immunized animals were challenged with an inhaled dose of 3.2 X 10(6) cfu (160 LD50 [50% lethal dose]) of virulent Y. pestis strain 195/P and two survived; the other three received a challenge dose of 4.9 X 10(6) cfu (245 LD50) and one survived. The three surviving monkeys had high titers of antibody to Fraction I. At necropsy of the animals that succumbed to the challenge infection, almost complete consolidation of the lungs was apparent, and sizable effusions were present in the thoracic cavities. Indeed, the striking pathology indicated the severest form of pneumonic plague. Since it can be assumed that the animal surviving challenge with the larger inoculum would have survived the smaller dose, we conclude that the immunization procedure protected half of the vervets that were exposed to challenge.

Immunity in Plague: Protection of the Vervet (Cercopithecus aethiops) against Pneumonic Plague by the Oral Administration of Live Attenuated Yersinia pestis

IN the course of work on histiocytes which accumulate in the peritoneal cavity following the injection therein of mineral oil, tritium-labelled thymidine was injected at various intervals after the oil. (Tritium-labelled thymidine was obtained from Schwartz Biochemical Co. and was administered intraperitoneally in the amount of 0.5 mc./gm. body-weight in a volume for 50 ml. Tyrode solution warmed to 37° C.) The histiocytes were collected from the rabbits using Tyrode solution and were maintained on cover-slips in Leighton tubes, in a medium consisting of 40 per cent normal rabbit serum in Tyrode solution. Smears examined by autoradiography showed frequent instances of histiocytos containing two or more nuclei. It became apparent that at least some of these binucleate and polynucleate cells did not arise from dividing cells which failed to separate because in many cases only one of the nuclei was labelled (Fig. 1).

Sanford S. Elberg

Papers

Cellular Immune Response to Yersinia pestis Modulated by Product (s) from Thymus-Derived Lymphocytes

Response of Peritoneal Exudate Cells to Brucella melitensis. Influence of Nature of Inflammatory Irritant.

Immunity in Plague: Protection of the Vervet (Cercopithecus aethiops) against Pneumonic Plague by the Oral Administration of Live Attenuated Yersinia pestis

Fusion of peritoneal histocytes with formation of giant cells.

Studies on enhancement of bacterial infection by hog gastric mucin.