Susceptibility of mice to pneumococcal infection after modification of the reticuloendothelial system with simple lipids

Depletion of phagocytes in the reticuloendothelial system causes increased inflammation and mortality in rabbits with Pseudomonas aeruginosa pneumonia

Phagocytes of the reticuloendothelial system are important in clearing systemic infection; however, the role of the reticuloendothelial system in the response to localized infection is not well-documented. The major goals of this study were to investigate the roles of phagocytes in the reticuloendothelial system in terms of bacterial clearance and inflammatory modulation in sepsis caused by Pseudomonas pneumonia. Macrophages in liver and spleen were depleted by administering liposome encapsulated dichloromethylene diphosphonate (clodronate) intravenously 36 h before the instillation of Pseudomonas aeruginosa into the lungs of anesthetized rabbits. Blood samples were analyzed for bacteria and cytokine concentrations. Lung injury was assessed by the bidirectional flux of albumin and by wet-to-dry weight ratios. Blood pressure and cardiac outputs decreased more rapidly and bacteremia occurred earlier in the clodronate-treated rabbits compared with the nondepleted rabbits. Plasma TNF-alpha (1.08 +/- 0.54 vs. 0.08 +/- 0.02 ng/ml) and IL-8 (6.8 +/- 1.5 vs. 0.0 +/- 0.0 ng/ml) were higher in the depleted rabbits. The concentration of IL-10 in liver of the macrophage-depleted rabbits was significantly lower than in normal rabbits at 5 h. Treatment of macrophage-depleted rabbits with intravenous IL-10 reduced plasma proinflammatory cytokine concentrations and reduced the decline in blood pressure and cardiac output. These results show that macrophages in the reticuloendothelial system have critical roles in controlling systemic bacteremia and reducing systemic inflammation, thereby limiting the systemic effects of a severe pulmonary bacterial infection.

Viability of yeast form cells of Paracoccidioides brasiliensis after sonication

To perform in-vitro studies with Paracoccidioides brasiliensis yeast cells it is necessary to avoid the presence of clumps of cells while maintaining their integrity. Because of the multiple budding type of growth, the bud cells are always attached to the mother cell and the yeast cells keep growing, resulting in the formation of large clumps. In order to obtain free cells, the cultures are usually sonicated. The present study shows that sonication induces lesions in a significant number of cells, as evaluated by labelling of the cells with acridine orange and Janus green vital dyes. In some cases labelling was initially observed in only one cell of the clump; however, the other cells also became labelled after a few minutes. These observations were confirmed by scanning and transmission electron microscopy of treated cells. Colony forming units (c.f.u.) on BHI plates also confirmed the decrease in cell viability following sonication.

RELATIONSHIP OF STRUCTURE TO FUNCTION IN BACTERIAL O ANTIGENS. III. BIOLOGICAL PROPERTIES OF ENDOTOXOIDS

Johnson, Arthur G. (The University of Michigan, Ann Arbor), and Alois Nowotny. Relationship of structure to function in bacterial O antigens. III. Biological properties of endotoxoids. J. Bacteriol. 87:809-814. 1964.-Endotoxin (somatic O antigen) was rendered much less lethal for mice and rabbits after treatment with boron trifluoride, potassium methylate, or pyridinium formate. In addition, the ability to induce the second fever peak of the biphasic febrile response characteristic of endotoxin was abolished. The capacity to prepare for the local Shwartzman reaction was also reduced after such treatments. On the other hand, stimulation of nonspecific resistance, and adjuvant action in mice was retained. The ability to elicit specific antibody was diminished after boron trifluoride treatment but only slightly retarded by the other two procedures.

Murine resistance to type III group B streptococci

We examined the role of serum, complement and the reticuloendothelial system in mouse resistance to type III group B streptococci (GBS). Normal serum obtained from 21 day-old mice failed to protect chick embryos against a lethal intravenous (IV) inoculation of GBS-III-SS620/50. Mice that were decomplemented using cobra venom factor remained resistant to intraperitoneal (IP) inoculation of 10(6) colony-forming units (CFU) of GBS-III-22620/50, GBS III-Bell and GBS-III-Minnesota. In contrast, mice prepared with IP oleic acid were killed with 10(4) CFU of GBS-III-SS620/50 IP. However, when mice were injected IV with oleic acid, they remained resistant to IP inoculation of GBS-III-SS620/50. These results suggest that peritoneal macrophages play a role in murine defense against IP infection with GBS-III-SS620/50.

Reticuloendothelial system phagocytic function in patients with Hodgkin's disease

Phagocytic function of the reticuloendothelial system as measured by the clearance of (125)I-labeled aggregated human serum albumin (AA) was studied in patients with Hodgkin's disease. Each more advanced stage of the disease was associated with more rapid clearance of the AA. Production of remission by radiation therapy or by chemotherapy was associated in some patients with slowing of the clearance rate, whereas relapse seemed to be associated with acceleration. Thus, impaired phagocytosis cannot be implicated in the several defects in immunity known to be present in Hodgkin's disease. Furthermore, determination of the clearance rate of AA in patients with Hodgkin's disease may have clinical usefulness as another indicator of extent or activity of disease.

Induction of Nonspecific Resistance by Endotoxin in Unresponsive Mice

Margherita , S. S. (Temple University School of Medicine, Philadelphia, Pa.), and H. Friedmann . Induction of nonspecific resistance by endotoxin in unresponsive mice. J. Bacteriol. 89: 277–280. 1965.— Serratia marcescens endotoxin was tested for protective effect in animals of varying immunological competence. A quantity of endotoxin capable of inducing resistance in mice to a standardized challenge of Diplococcus pneumoniae was equally effective in animals immunologically paralyzed with a high dose of homologous pneumococcal polysaccharide. Failure of the unresponsive state to influence the degree of resistance induced by endotoxin suggests that a specific humoral factor does not play a significant role in the nonspecific resistance.

The specificity of cellular immunity

1. Non-specific stimulation of mice by a detergent lacking in vitro antibacterial activity, Triton WR 1339, produces a steady state in the course of experimental tuberculosis at about the same level as specific immunization, and does so independently of delayed allergy.

2. This effect is achieved in a much shorter time than is required by the normal immunological processes and the relative duration of enhanced resistance in each case is yet to be worked out.

3. Triton fails to enhance an existing, specifically acquired immunity.

4. There is no evidence so far that the mechanism involved is the same in both instances. If it were found to be the same, then the present concept of a specific cellular immunity would need to be revised.