Activation of phagocytosis by preparations of human alpha and gamma interferons

Preparations of human alpha- and gamma-interferon differing by the method of production and purification had different capacity of activating phagocytosis of blood polymorphonuclear leukocytes from patients with dermatoses. Native preparations of alpha- and gamma-interferon had the highest phagocytosis-activating potency. A high level of this activity was also demonstrated with human leukocyte interferon II for injections purified by highly specific methods. A concentrated preparation of human leukocyte interferon for injections with a specific activity above 1 million IU/1 mg of protein and recombinant alpha 2-interferon (reaferon) exhibited minimal phagocytosis activating effect.     

Activation of human monocytes/macrophages by hypo-osmotic shock

Phagocytosis and secretion of interleukins and growth factors put the macrophage in the centre of the wound healing process. For the last four years over 400 human ulcers have been treated in elderly and paraplegic patients by local application of monocytes prepared from a blood unit, in a unique, closed, sterile system. The process of preparation includes a step of hypo-osmotic shock, which induces monocyte/macrophage activation. This is different from any other known method of activation. In the present study we evaluated the efficacy of the hypo-osmotic shock. We found enhanced levels of IL-1 (P = 0.004) and IL-6 (P = 0.001) in the incubation medium (100% autologous serum) of the activated cells, as compared with controls, prepared in the same system. The IL-1 reached a plateau after 6 and 12 h incubation at 37 degrees C, in both experimental and control incubation medium. The level of IL-6 was further elevated after 12 and 24 h incubation in experimental and control incubation mediums (P = 0.001). The phagocytosis of fluorescent beads was markedly enhanced after hypo-osmotic shock (P = 0.005). The osmotic shock induced macrophages were compared to those stimulated with LPS, and osmotic shock was proved to be at least as efficient method of stimulation as LPS.     

Phagocytosis of unopsonized zymosan by human monocyte-derived macrophages: maturation and inhibition by mannan

Human monocyte-derived macrophages phagocytosed zymosan in the absence of serum opsonins. The capacity to ingest zymosan developed after the cells were cultured in vitro for 3 days and was inhibited completely by mannan. We conclude that human monocyte-derived macrophages phagocytose unopsonized zymosan predominantly via mannose receptors.     

Growth inhibition of human lymphoblastoid Daudi cellsin vitro by interferon preparations

Summary Human interferon (HIF) preparations inhibited the propagation of Daudi cells in stationary suspension cultures, while a control preparation showed no such effect. The growth inhibition (= anticellular) activity of differently pretreated HIF preparations was determined by the reduction of¹⁴C-labelled thymidine (¹⁴C-TDR) uptake in a microassay system. These studies demonstrated that the degree of anticellular activity is directly proportional to the antiviral activity of different HIF preparations. These preparations were obtained from peripheral leukocytes (lHIF) or diploid fibroblasts (fHIF). Together with gel chromatography results, and the sensitivity of the anticellular activity to tryptic digestion and heat inactivation, these results suggest that the anticellularly active substance is a protein which is very similar to, or identical with, interferon.With 7 Figures     

Recognition of apoptotic cells by human macrophages: inhibition by a monocyte/macrophage-specific monoclonal antibody

Cells undergoing death by apoptosis are rapidly engulfed by phagocytes in vivo, a highly efficient process which prevents leakage of potentially dangerous intracellular contents from dying cells to neighboring tissue. We have tested a panel of monoclonal antibodies (mAb) specifying a range of human monocyte/macrophage surface antigens for their capacity to inhibit the in vitro recognition of apoptotic cells by human peripheral blood monocyte-derived macrophages. The results identify the antigen defined by the 61D3 mAb, a widely-used marker of monocyte/macrophage lineage cells, as an important mediator of apoptotic cell recognition. In our system, apoptotic, but not viable, cells were recognized by the cultured macrophages and 61D3 was found to inhibit the recognition of all apoptotic cell types tested, including Ca²⁺ ionophore-treated or growth factor-depleted B and T lymphocyte lines, tonsillar germinal center B cells, irradiated peripheral blood lymphocytes and senescing neutrophils. Furthermore, the apoptotic cell recognition pathway specified by 61D3 could be distinguished from that involving the macrophage α_vβ₃ vitronectin receptor which has been shown previously to play an important role in the recognition of apoptotic cells. These results provide further evidence that the mechanisms underlying rapid clearance of apoptotic cells involve multiple phagocyte receptors.     

Activation of macrophages by quinonyl-N-acetylmuramyl dipeptide.

The effect of 6-O-QS-10-N-acetylmuramyl-L-valyl-D-isoglutamine methyl ester (quinonyl-MDP-66) on various functions of macrophages was examined. Mouse peritoneal macrophages, when treated either in vitro or in vivo with quinonyl-MDP-66 suspended in phosphate-buffered saline, showed a capacity for cytolysis and cytostasis against tumor targets and released H2O2 in the presence of phorbol myristate acetate. The macrophages induced by quinonyl-MDP-66 also had both antibody-dependent cell-mediated cytotoxicity and phagocytic activity against erythroid targets. The fact that synthetic quinonyl-MDP-66 stimulates the macrophages to become more cytotoxic than do other MDP analogs suggests that the lipophilic residue (QS-10) in quinonyl-MDP-66 may be important for the development of this activity.     

Activation of macrophages by silicones: phenotype and production of oxidant metabolites

Background  

The effect of silicones on the immune function is not fully characterized. In clinical and experimental studies, immune alterations associated with silicone gel seem to be related to macrophage activation. In this work we examined in vivo, phenotypic and functional changes on peritoneal macrophages early (24 h or 48 h) and late (45 days) after the intraperitoneal (i.p.) injection of dimethylpolysiloxane (DMPS) (silicone). We studied the expression of adhesion and co-stimulatory molecules and both the spontaneous and the stimulated production of reactive oxygen intermediates and nitric oxide (NO).     

Activation of neonatal and adult human macrophages by alpha, beta, and gamma interferons.

Increasing evidence suggests that gamma interferon (IFN-gamma) is the major or sole factor in human lymphokines which activates blood monocyte-derived macrophages (M phi) to inhibit or kill Toxoplasma gondii and certain other intracellular pathogens. In the current studies, we found that IFN-gamma effectively activated tissue M phi from adults (peritoneal M phi) and from newborns (placental M phi) as well as blood-derived M phi from adults and from newborns to kill or to inhibit the replication of T. gondii. Results with purified and recombinant IFN-gamma and with adult and newborn M phi were similar. IFN-gamma-treated M phi were equally or more active against T. gondii than were freshly isolated monocytes and M phi. Recombinant IFN-alpha A and IFN-beta were less effective than IFN-gamma. IFN-gamma also inhibited survival and replication of T. gondii in WISH cells more effectively than did IFN-alpha and IFN-beta. These findings are consistent with an important role for IFN-gamma in the control of Toxoplasma infection and indicate that the anti-Toxoplasma activity of resting and IFN-gamma-activated adult and neonatal M phi is similar. The increased susceptibility of neonates to T. gondii is not due to a defect in M phi effector function.     

Activation of murine peritoneal macrophages by Salmonella typhimurium

The results of these studies indicate that the interaction between activated macrophages and S. typhimurium depends on the characteristics of the micro-organism and the kind of activation.     

Activation of macrophages by gliadin fragments: isolation and characterization of active peptide

Celiac disease, induced by dietary gluten, is characterized by mucosal atrophy and local inflammation associated with cell infiltration and activation. Unlike other food proteins, gluten and its proteolytic fragments, besides inducing a specific immune response, were shown to activate components of innate immunity and cause, e.g., direct stimulation of TNF-alpha and IL-10 and a significant rise in NO production by peritoneal macrophages. The identity of the active fragments was established by separating the peptic digest of gliadin by RP-HPLC chromatography. The purest fraction with the highest activity was analyzed by mass spectrometry, and the gliadin peptide sequence was identified as VSFQQPQQQYPSSQ. This peptide (T) and its N- and C-terminally shortened forms (A, B, C and D, E, F) were synthesized. Peptide B (FQQPQQQYPSSQ) elicited the highest TNF-alpha, IL-10, and RANTES secretion and increase in IFN-gamma-primed NO production by mouse macrophages. In contrast, C-terminally shortened peptides had a lower ability to stimulate macrophages than the native form.     

Activation of human THP-1 cells and rat bone marrow-derived macrophages by Helicobacter pylori lipopolysaccharide.

The mechanism by which Helicobacter pylori, which has little or no invasive activity, induces gastric-tissue inflammation and injury has not been well characterized. We have previously demonstrated that water-extracted proteins of H. pylori are capable of activating human monocytes by a lipopolysaccharide (LPS)-independent mechanism. We have now compared activation of macrophages by purified LPS from H. pylori and from Escherichia coli. LPS was prepared by phenol-water extraction from H. pylori 88-23 and from E. coli O55. THP-1, a human promyelomonocytic cell line, and macrophages derived from rat bone marrow each were incubated with the LPS preparations, and cell culture supernatants were assayed for production of tumor necrosis factor alpha (TNF-alpha), prostaglandin E2 (PGE2), and nitric oxide. THP-1 cells showed maximal activation by the LPS molecules after cell differentiation was induced by phorbol 12-myristate 13-acetate. Maximal TNF-alpha and PGE2 production occurred by 6 and 18 h, respectively, in both types of cells. In contrast, NO was produced by rat bone marrow-derived macrophages only and was maximal at 18 h. The minimum concentration of purified LPS required to induce TNF-alpha, PGE2, and NO responses in both types of cells was 2,000- to 30,000-fold higher for H. pylori than for E. coli. Purified LPS from three other H. pylori strains with different polysaccharide side chain lengths showed a similarly low level of activity, and polymyxin B treatment markedly reduced activity as well, suggesting that activation was a lipid A phenomenon. These results indicate the low biological activity of H. pylori LPS in mediating macrophage activation.     

Characterization of inhibition of Mycobacterium avium replication in macrophages by normal human serum.

Serum from some AIDS patients permits the rapid multiplication of Mycobacterium avium in cultured human macrophages. Serum from human immunodeficiency virus-negative individuals inhibits replication. The characteristics of the serum-induced inhibition were examined here. M. avium 7497 serovar 4 grew exponentially in macrophages when they were cultured in serumless medium. Growth was measured by determining the CFU after infected macrophages were lysed at 0 to 7 days after infection. Normal AB serum (5 to 10%) added to infected macrophages resulted in an initial 4-day lag of bacterial growth followed by rapid replication from 4 to 7 days. Serum also inhibited bacterial replication in medium without macrophages. This inhibition was not biphasic but was sustained over 7 days. Macrophage-associated M. avium became less responsive to serum inhibitor within 24 h after infection of macrophages. Within 2 days of culture, M. avium no longer responded to inhibitor. Replication of macrophage-derived M. avium (Vi) was in some instances serum inhibitable and at other times was enhanced by serum, when it was used to infect fresh macrophages. The Vi phenotype remained serum inhibitable without macrophages. Preinfection of macrophages with heat-killed M. avium did not alter serum-induced bacterial inhibition or escape from inhibition.     

Activation of human complement by rat peritoneal mast cells and its inhibition by a rat serum factor

The effects of normal sera from humans, rats, and guinea pigs on unsensitized rat peritoneal mast cells were studiedin vitro. Five to 20% fresh human sera induced mast cell death and substantial histamine release. The factor was heat labile. Neither hereditary C3-deficient sera nor experimentally Clq-depleted sera showed cytotoxicity. The CH50 activity of human serum was decreased to about one half after a 15-min incubation with 2×10⁶ mast cells/ml at 37°C. The cytotoxic activity and CH50 reduction were completely eliminated by an addition of 10 mM Mg-EGTA to the serum. These data demonstrated that unsensitized rat mast cells served as both the initiator and target of complement activity when human serum was used as a complement source. Requirements of both Ca⁺⁺ and Clq suggested the activation of the classical pathway of complement. Fresh 5–20% sera from rats and guinea pigs, on the other hand, showed neither cytotoxicity nor CH50 reduction. Furthermore, these sera strongly inhibited the human serum-induced reaction. The latter results indicated the presence of a modulating factor in rat and guinea pig sera, which inhibits mast cell associated complement activation.     

Activation of mouse peritoneal macrophages by mannophosphoinositides of mycobacteria

Peritoneal macrophages isolated from mannoside-methylated bovine serum albumin (MBSA)-immunized mice showed significantly enhanced phagocytosis of Mycobacterium smegmatis compared to control or MBSA-immunized groups. Immune macrophages also exhibited bacteriostatic activity against M. smegmatis. Pretreatment of mycobacteria with mannoside antibodies did not further alter the phagocytosis and bacteriostatic effect of immune macrophages.     

Activation of human T and non-T lymphocytes by sepharose-bound concanavalin A and the differential effect of macrophages.

The mitogenic effect of insoluble concanavalin A (Con A) bound to Sepharose beads on human peripheral blood mononuclear cells has been investigated. Sepharose-Con A, with a maximum activity at 100-400 micrograms/ml and an optimal incubation time of 3 or 4 days, stimulated the mononuclear cells with a high mitogenic response. Sepharose-Con A also stimulated the monocyte-depleted lymphocytes and their T- and non T-enriched fractions with a definite mitogenic response, although the levels of response were much lower than those of unpurified mononuclear cells. Addition of the adherent monocytes strongly augmented the Sepharose-Con A responses of monocyte-depleted lymphocytes and their T-enriched fractions, whereas it gave no effect on those of non-T-enriched fractions. Culture fluids of adherent monocytes also augmented the Sepharose-Con A responses of monocyte-depleted lymphocytes. These results indicate that, although insoluble Sepharose-Con A activates both human T and B cells, the response of T cells but not B cells may be dependent in part on the presence of monocytes or a monocyte-derived soluble factor(s). Thus, it is concluded that Sepharose-Con A may be a useful mitogen to elucidate the role of macrophages or their soluble factors in activation of human T and B cells.     

Activation of macrophages by Entamoeba histolytica extracts in mice

The effect of Entamoeba histolytica extracts on the production of inflammatory macrophages and the release of hydrogen peroxide (H2O2) and superoxide (O2-) from these cells was examined in C57BL/6 mice. Two different strains of E. histolytica, either virulent (IP:0682:1) or nonvirulent (DKB), were used in this study. The number of macrophages recovered from the peritoneal cavity of mice treated 5 days previously with 150 micrograms of either strain of amoebic extracts was significantly higher than in the saline-treated groups. Macrophages from mice treated with 150 micrograms of the IP:0682:1 strain of amoebic extracts exhibited a powerful burst of oxidative metabolis when triggered with phorbol myristate acetate (PMA). Extract from the non-virulent strain was much less effective in activating macrophages for the production of oxidative metabolites. Thus, a crude extract preparation from E. histolytica, particularly the virulent strain, induces a strong macrophage inflammatory response in which the cells also produce high levels of H2O2 and O2-.     

Activation of murine macrophages by lipoprotein and lipooligosaccharide of Treponema denticola

We have recently demonstrated that the periodontopathogenic oral spirochete Treponema denticola possesses membrane-associated lipoproteins in addition to lipooligosaccharide (LOS). The aim of the present study was to test the potential of these oral spirochetal components to induce the production of inflammatory mediators by human macrophages, which in turn may stimulate tissue breakdown as observed in periodontal diseases. An enriched lipoprotein fraction (dLPP) from T. denticola ATCC 35404 obtained upon extraction of the treponemes with Triton X-114 was found to stimulate the production of nitric oxide (NO), tumor necrosis factor alpha (TNF-alpha), and interleukin-1 (IL-1) by mouse macrophages in a dose-dependent manner. Induction of NO by dLPP was at 25% of the levels obtained by Salmonella typhosa lipopolysaccharide (LPS) at similar concentrations, while IL-1 was produced at similar levels by both inducers. dLPP-mediated macrophage activation was unaffected by amounts of polymyxin B that neutralized the induction produced by S. typhosa LPS. dLPP also induced NO and TNF-alpha secretion from macrophages isolated from endotoxin-unresponsive C3H/HeJ mice to an extent similar to the stimulation produced in endotoxin-responsive mice. Purified T. denticola LOS also produced a concentration-dependent activation of NO and TNF-alpha in LPS-responsive and -nonresponsive mouse macrophages. However, macrophage activation by LOS was inhibited by polymyxin B. These results suggest that T. denticola lipoproteins and LOS may play a role in the inflammatory processes that characterize periodontal diseases.