concanavalin-a and Pseudomonas-Infections

Immature myeloid cells have been implicated as a source of postburn inflammation, and the appearance of these cells correlates with enhanced upregulation of hematopoiesis. The role of proliferative cells in postburn immune changes has not been directly tested. Gemcitabine, a ribonucleotide reductase inhibitor, has been shown to deplete proliferative immature myeloid cells in tumor models while sparing mature cells, leading to restored lymphocyte function and tumor regression. We treated burn mice at postburn day 6 (PBD6) with 120 mg/kg gemcitabine. On PBD8, splenocytes were taken and stimulated with LPS, peptidoglycan, or concanavalin A. The blood and spleen cell populations were enumerated by flow cytometry or automated cell counter. In addition, mice treated with gemcitabine were given LPS or infected with Pseudomonas aeruginosa at PBD8, and mortality was monitored. Gemcitabine depleted burn-induced polymorphonuclear leukocytes and inflammatory monocytes without affecting mature F4/80 macrophages. This was accompanied by reduced TNFα, IL-6, and IL-10 production by burn splenocytes. Burn splenocytes stimulated with mitogens exhibited increased nitric oxide production relative to sham mice. In vivo treatment of burn mice with gemcitabine blocked these burn-induced changes without damaging lymphocyte function. Treatment of burn mice with gemcitabine ameliorated burn-induced susceptibility to LPS and infiltration of polymorphonuclear leukocytes into the liver and lung. Finally, gemcitabine treatment blocked the protective effect of burn injury upon P. aeruginosa infection. Our report shows that proliferative cells are major drivers of postburn immune changes and provides evidence that implicates immature myeloid cells in these processes.

Topics: Animals; Burns; Concanavalin A; Deoxycytidine; Drug Evaluation, Preclinical; Gemcitabine; Interleukin-10; Interleukin-6; Leukocyte Count; Lipopolysaccharides; Lymphocyte Activation; Macrophages; Male; Mice; Mice, Inbred C57BL; Monocytes; Myeloid Cells; Nitric Oxide; Peptidoglycan; Pseudomonas Infections; Ribonucleotide Reductases; Spleen; T-Lymphocyte Subsets; Tumor Necrosis Factor-alpha

In vitro and in vivo T cell responses were determined during the course of bronchopulmonary infection with mucoid Pseudomonas aeruginosa. T cell responses were compared in two inbred mouse strains, namely BALB/c mice, which are resistant to the establishment of chronic bronchopulmonary Ps. aeruginosa infection, and C57Bl/6 mice, which have high numbers of bacteria in the lungs through 14 days post-infection. Unseparated lung cells and lung T cells from BALB/c mice exhibited significantly higher in vitro proliferative responses to both heat-killed Ps. aeruginosa and concanavalin A (Con A) than cells from C57Bl/6 mice through 20 days post-intratracheal infection with 10(4) colony-forming units (CFU) Ps. aeruginosa. Proliferation of unseparated lung cells but not lung T cells from BALB/c mice infected 6 days previously with 10(5) CFU Ps. aeruginosa was suppressed in response to Con A; these cells were unresponsive to specific antigen. Suppression of lymphocyte proliferation in the lungs of C57Bl/6 mice infected with 10(4) CFU Ps. aeruginosa and in BALB/c mice infected with 10(5) CFU was found to be mediated by adherent lung cells via the production of nitric oxide and prostaglandins. Determination of in vivo T cell-mediated responses in infected mice demonstrated that resistant BALB/c mice had high DTH and low Pseudomonas-specific antibody responses, while C57Bl/6 mice had low DTH and high antibody levels, in particular, IgG2b and IgM.

Topics: Animals; Antibodies, Bacterial; Bronchial Diseases; Cell Division; Cells, Cultured; Chronic Disease; Concanavalin A; Disease Models, Animal; Female; Hypersensitivity, Delayed; Immunity, Cellular; Lung; Lung Diseases; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Pseudomonas Infections; T-Lymphocytes

The high morbidity after severe thermal insult is believed to be related partially to a resultant decrease in immunocompetence. We tested the ability of phytohemagglutinin (PHA) and Concanavalin (Con A) to stimulate lymphocyte transformation in 17 patients with moderate to severe thermal injury (greater than 25% BSA). The patients acted as their own controls and the per cent change in their mitogen response was measured over time. Eight acutely burned patients who subsequently developed severe sepsis (Group I) had decreased ability (mean, 12% of normal) to proliferate in response to PHA, and six of these died of severe sepsis. The depressed response appeared 4 to 7 days postinjury and predated clinical evidence of sepsis by 2 to 4 days. Cells from four patients who had mild infectious complications (Group II) demonstrated greatly augmented mitogen responses (mean + 243%) approximately 7 to 10 days postinjury. Five burn patients whose clinical course was sepsis free (Group III) exhibited only minimal changes in their mitogen responses (mean +30%). Although the Con A responses of the patients' cells corresponded less to their pathology, Group I patients whose cells exhibited depressed PHA responsiveness also had diminished Con A responses. Group II patients' cells also showed increases in Con A-induced stimulation. Group III patients, who had only slightly augmented PHA responses, had minimal decreases of the Con A-induced lymphocyte transformation. Many severely burned patients develop septicemia as a result of their large wound surfaces. The appearance of decreases in mitogen-induced proliferation, however, appears to characterize those patients who will be unable to handle the septic challenge.

Topics: Adult; Aged; Bacterial Infections; Burns; Concanavalin A; Escherichia coli Infections; Female; Humans; Immunocompetence; Klebsiella Infections; Lymphocyte Activation; Male; Middle Aged; Phytohemagglutinins; Prognosis; Pseudomonas Infections; Sepsis; Staphylococcal Infections; T-Lymphocytes; Time Factors