Cell-mediated immune phenomena induced by lymphokines from splenic lymphocytes of mice with chronic staphylococcal infection

Time course of antilisterial activity by immunologically activated murine peritoneal macrophages

Murine peritoneal macrophages were rapidly rendered listericidal after exposure to lymphokine-rich supernatants (LRSs) derived from antigen-pulsed Listeria monocytogenes-immune spleen cells. A 6-h incubation period with LRSs was sufficient to induce microbicidal activity in resident macrophages. In vitro induction of macrophage listericidal activity by constant exposure to LRSs persisted for 18 h, after which time spleen cell factors were no longer capable of modifying intracellular inactivation of Listeria. Results obtained by utilizing a short assay indicated that the killing kinetics is extremely rapid, with large numbers of bacteria destroyed during the first 15 min of infection. Intracellular killing at this time appeared to be greatly dependent upon the stage of growth from which the microorganisms were harvested. Induction of bactericidal macrophages by infection of mice with a sublethal dose of virulent Listeria cells and subsequent intraperitoneal elicitation with heat-killed homologous bacteria was similarly a transient event. Macrophages harvested 18 h after antigenic challenge displayed dramatic antibacterial activity during the first 22 h in culture. After 22 h, activity was lost, and stasis was observed during the ensuing 23 h. At 68 h, macrophages were devoid of antilisterial action. Activity, however, could be recalled after incubation with LRSs.

Impaired response of lymphocytes from non-insulin-dependent diabetics to staphage lysate and tetanus antigen

We examined the blastogenic responses of lymphocytes to Staphylococcus aureus antigen in 49 uninfected non-insulin-dependent diabetic subjects and in 56 uninfected nondiabetic subjects. We found a significantly decreased response to this antigen in the diabetic patients (P less than 0.05). Diabetics whose blood sugar levels were less than 150 mg/dl showed significantly decreased responses, as did diabetics whose blood sugar levels were greater than 200 mg/dl. The use of fetal calf serum in place of autologous plasma did not correct the defect. In a smaller number of patients, we observed a decreased response to tetanus toxoid, which was significant (P less than 0.05). The response to phytohemagglutinin was not significantly different from normal controls (P greater than 0.4). These results indicated that non-insulin-dependent diabetics, as well as insulin-dependent diabetics (previously reported), show decreased responses to S. aureus antigen and to tetanus toxoid. This defect apparently is not related to blood glucose levels or other serum factors.

Fate of Listeria monocytogenes in murine peritoneal macrophage subpopulations

Peritoneal macrophages derived from CD-1 and C57BL/6 mice were separated into distinct groups based on their buoyant densities on discontinuous gradients of Percoll and assayed for antibacterial activity against Listeria monocytogenes. Subpopulations of peritoneal macrophages derived from Listeria-immune mice present a wide variation in their ability to control intracellular infection. Distinct subsets were found which exhibited bacteriostatic and listericidal activity. The fractionation procedure yielded a population of peroxidase-positive macrophages which were devoid of antilisterial action. Subpopulations of resident and elicited macrophages were also functionally heterogeneous in their ability to restrict intracellular growth of bacterial. In some experiments, subclasses were examined for secretion of plasminogen activator and phagocytosis of latex particles. These activities varied considerably with the status of activation of the macrophages, but failed to correlate with antimicrobial activity within given subpopulations.

Murine defense mechanism against Candida albicans infection. II. Opsonization, phagocytosis, and intracellular killing of C. albicans

The phagocytic and intracellular killing activities of normal mouse phagocytes against Candida albicans were studied to elucidate the role of these activities in nonspecific and specific defense mechanisms. In the presence of fresh normal mouse serum, viable C. albicans cells were ingested by mouse peripheral blood leukocytes (PBLs) and peritoneal macrophages (PMPs) at the same rate. Serum-chelation experiments indicated that the factors involved in the alternative complement pathway are opsonins for C. albicans. PBLs killed intracellular C. albicans more effectively than PMPs. Lymphokine-activated PMPs manifested marked intracellular killing activity and the occurrence of increased superoxide anion- and singlet oxygen production, in the absence of increased myeloperoxidase (MPO) production, suggests that the enhanced, MPO-independent, oxidative mechanism may play an important role in the candidacidal activity. Specific rabbit antibodies played no role in the phagocytosis and intracellular killing of C. albicans. These results suggest that PMNs and factors involved in the alternative complement pathways, and lymphokine-activated macrophages play major roles in the protection of mice against C. albicans infection.

Killing of intraphagocytic Staphylococcus aureus by dihydrostreptomycin entrapped within liposomes

Liposomes (phospholipid vesicles) may serve as vehicles of antibiotic transport to intracellular sites. Liposomes containing entrapped dihydrostreptomycin enhanced killing of Staphylococcus aureus contained within phagocytic vacuoles.

Passive immunity against pseudomonas sepsis during granulocytopenia

Specific passive immunity against Pseudomonas aeruginosa sepsis was assessed in granulocytopenic dogs. Dogs were infused with either normal or antipseudomonas immune plasma 24 h before pseudomonas challenge. They were challenged intravenously with 10(7) serotype 6 P. aeruginosa during granulocytopenia. Treatment was evaluated by observation of survival periods, febrile responses, type 6 pseudomonas antibody titers, and quantitative cultures of blood and tissues. The results demonstrated that passively immunized dogs did not survive infection. Both normal-plasma and immune-plasma recipients had bacteremia at death, with median values of 980 and 470 pseudomonas per ml of blood, respectively. All dogs had marked febrile responses 24 h after pseudomonas challenge and had high concentrations of pseudomonas in their lung tissue at death, with median values of 10(8) pseudomonas per g of wet tissue weight. After plasma infusion, immune-plasma recipients had high concentrations of anti-pseudomonas antibody, with total antibody titers ranging from 256 to 1,024 and a median value of 1,024. These titers were comparable to titers attained in a previous study from our laboratory using active immunization with pseudomonas lipopolysaccharide vaccine, where the median total anti-pseudomonas antibody titer was 2,048. Actively immunized animals, however, were significantly protected against pseudomonas sepsis and had prolonged survival periods and prevention of bacteremia. The present study demonstrates that circulating type-specific antibody is not solely responsible for the protection afforded to granulocytopenic dogs actively immunized against pseudomonas.

Nonspecific resistance to Listeria monocytogenes in mice infected and elicited with Staphylococcus aureus

Normal mice and mice displaying delayed hypersensitivity to Staphylococcus aureus were challenged with a lethal dose of Listeria monocytogenes. Nonspecific antimicrobial activity was assessed by inhibition of bacterial growth in the spleen and by increased survival rates. Administration of specific staphylococcal antigen prior to challenge was a prerequisite for the induction of nonspecific resistance. Both the time of administering eliciting antigen and the route were important consideration for evoking the response. Similar responses were seen in 3 strains of inbred mice following immunization with both encapsulated and nonencapsulated staphylococci. Although enhanced resistance as measured by viable counts in the spleens was achieved after 2 injections, protection as measured by survival required 4 injections of S. aureus followed by elicitation with staphylococcal antigens. Nonspecific resistance could be detected as late as 9 weeks after the disappearance of delayed hypersensitivity.

Phagocytosis and intracellular killing of Staphylococcus aureus by normal mouse peritoneal macrophages

Although Staphylococcus aureus is incapable of intracellular multiplication in cultured mouse peritoneal macrophages, it is killed at a much slower rate than the avirulent Staphylococcus epidermidis. In addition to the presence of capsular material which inhibits phagocytosis of specific strains of S. aureus, the data show that a number of cellular and environmental factors affect the functional capacities of mononuclear phagocytic cells. The data obtained by varying the initial level of infection indicate that the number of ingested bacteria may subsequently alter the kinetics of intracellular killing. In vitro maturation of macrophages in culture was also found to exert a pronounced effect on the kinetics of bacterial death.