The macrophage as a secretory cell

Medicinal Plants from Mexico, Central America, and the Caribbean Used as Immunostimulants

A literature review was undertaken by analyzing distinguished books, undergraduate and postgraduate theses, and peer-reviewed scientific articles and by consulting worldwide accepted scientific databases, such as SCOPUS, Web of Science, SCIELO, Medline, and Google Scholar. Medicinal plants used as immunostimulants were classified into two categories: (1) plants with pharmacological studies and (2) plants without pharmacological research. Medicinal plants with pharmacological studies of their immunostimulatory properties were subclassified into four groups as follows: (a) plant extracts evaluated for in vitro effects, (b) plant extracts with documented in vivo effects, (c) active compounds tested on in vitro studies, and (d) active compounds assayed in animal models. Pharmacological studies have been conducted on 29 of the plants, including extracts and compounds, whereas 75 plants lack pharmacological studies regarding their immunostimulatory activity. Medicinal plants were experimentally studied in vitro (19 plants) and in vivo (8 plants). A total of 12 compounds isolated from medicinal plants used as immunostimulants have been tested using in vitro (11 compounds) and in vivo (2 compounds) assays. This review clearly indicates the need to perform scientific studies with medicinal flora from Mexico, Central America, and the Caribbean, to obtain new immunostimulatory agents.

The antitumoral effect of the American mistletoe Phoradendron serotinum (Raf.) M.C. Johnst. (Viscaceae) is associated with the release of immunity-related cytokines

ETHNOPHARMACOLOGICAL RELEVANCE

Phoradendron serotinum is commonly used in Mexican traditional medicine for the empirical treatment of cancer. However, there are no studies regarding the antitumoral or immunomodulatory activities of Phoradendron serotinum.

MATERIALS AND METHODS

The in vivo toxicity of ethanolic extracts of Phoradendron serotinum (PSE) was evaluated in mice according to the Lorke procedure. The in vitro immunomodulatory effects of PSE were evaluated estimating the effects of PSE on the pinocytosis, NO production and lysosomal enzyme activity in murine macrophages RAW 264.7. The effects of PSE on the proliferation of murine splenocytes and NK cell activity were also assayed. The cytotoxic effects on TC-1 (lung murine cancer cells) were evaluated using the MTT assay, whereas the apoptotic effect of PSE on TC-1 cells was evaluated using TUNEL assay. Also, different doses of PSE were injected intraperitoneally daily into C57BL/6 mice bearing tumors of TC-1 cells during 25 days. The growth and weight of tumors was measured. In addition, the levels of IL-2, IL-6, IL-12, IL-23 and IFN-γ in murine serum and supernatants of K562 cell-murine splenocyte cocultures were measured.

RESULTS

PSE stimulated the proliferation, pinocytosis and lysosomal enzyme activity in murine macrophages with a similar potency than lypopolisaccharides 1 μg/ml. In addition, PSE stimulated the proliferation of murine splenocytes and induced the NK cell activity. PSE showed cytotoxic (IC(50)=1.9 μg/ml) and apoptotic effects against TC-1 cells. The LD(50) was 125 mg/kg by intraperitoneal route (i.p.) and 375 mg/kg by oral route. PSE administrated at 1, 5 and 10 mg/kg i.p. inhibited the tumor growth by 18%, 40% and 69%, respectively, in mice bearing TC-1 tumor. PSE increased the in vitro and in vivo release of IL-2, IL-6 and IFN-γ but lacked effect on IL-12 and IL-23 release.

CONCLUSIONS

Phoradendron serotinum shows moderate toxic effects in vivo, exerts cytotoxic and apoptotic effects on TC-1 cells. Phoradendron serotinum also has antitumor effects in mice bearing TC-1 tumor and induces immunomodulatory activities in vivo. The results suggest that antitumoral effects of PSE are related with the production of immunity-related cytokines.

Antitumor Effects and Immunomodulating Activities of Phellinus linteus Extract in a CT-26 Cell-Injected Colon Cancer Mouse Model

The antitumor effects of Phellinus linteus extract (Keumsa Linteusan) were investigated in a CT-26 cell-injected colon cancer mouse model. When administered orally (250~1,000 mg/kg body weight), Keumsa Linteusan significantly inhibited the growth of solid colon cancer. The highest dose was highly effective, reducing tumor formation by 26% compared with the control group. The anticomplementary activity of Keumsa Linteusan increased in a dose-dependent manner. Lysosomal enzyme activity of macrophages was increased by 2-fold (100 µg/ml) compared with the control group. Keumsa Linteusan can be regarded as a potent enhancer of the innate immune response, and can be considered as a very promising candidate for antitumor action.

Chemical characteristics and immuno-modulating activities of exo-biopolymers produced by Grifola frondosa during submerged fermentation process

The immuno-modulating activities and chemical characteristics of exo-biopolymer (EX-GF) produced by a submerged mycelial culture of Grifola frondosa were studied. The EX-GF was fractionated into EX-GF-Fr.I, II, and III by Sephadex G-100 gel chromatography. Anti-complementary activity of EX-GF-Fr.III was highest (71.1%) among them, and its activation system occurred through both classical and alternative pathways, where the classical pathway found to be major one. Lysosomal enzyme activity and nitric oxide production ability of macrophage were also found to be mediated by EX-GF-Fr.III. The molecular weight of the EX-GF-Fr.I, II, and III was estimated to be about 163, 40, and 2.8 kDa, respectively. Total sugar and protein contents of the three fractions were 80.3, 61.9 and 89.3%, and 17.3, 35.2, and 10.7%, respectively. The sugar and amino acid compositions of the EX-GF-Fr.I, II, and III were also analyzed in detail.

Macrophage-Stimulating Activity of Polysaccharides Extracted from Fruiting Bodies of Coriolus versicolor (Turkey Tail Mushroom)

The macrophage-stimulating effect of polysaccharides extracted from Coriolus versicolor (Turkey Tail mushroom) was investigated, and their effectiveness was compared with that of lipopolysaccharide (LPS). The purified polysaccharide (CV-S2-Fr.I) of C. versicolor obtained by Sepharose CL-6B gel chromatography stimulated macrophage lysosomal enzyme activity by 250% at a concentration of 100 microg/mL, which was higher than that of LPS at the same concentration. When CV-S2-Fr.I was used in combination with interferon-gamma, there was a marked cooperative induction of nitric oxide production. However, CV-S2-Fr.I had no effect on nitric oxide production by itself. The proportion of C3-positive macrophages in the CV-S2-Fr.I group increased by 7.2-fold compared with the control group.

Chemical Characteristics and Immuno-stimulating Properties of Biopolymers Extracted from Acanthopanax sessiliflorus

During our search for macrophage stimulating compounds from medicinal plants, we isolated biopolymers from Acanthopanax sessiliflorus. Isolated fraction AS-5 showed maximum potential, and stimulated lysosonal enzymatic activity by 230% at 300 microg/ml. The nitric oxide (NO) producing ability of AS-5 100 microg/ml was 58 microM when treated with interferon-gamma and lipopolysaccharide 20 micro/ml. The lymphocyte proliferating effects of isolated biopolymer fractions were also investigated. Highest lymphoproliferative activity (a 2.8-fold enhancement compared to salines treated group was exhibited by AS-3 at 200 micro/ml followed by AS-5 and AS-6. The AS-3 fraction stimulated only T-lymphocytes and had little or no effect on B-lymphocyte proliferation. Partially methylated alditol acetates were prepared to elucidate the glycosyl linkage-compositions of the AS-3 and AS-5 biopolymers, and were analyzed by GC-MS. The AS-3 and AS-5 biopolymer fractions were found to contain 2,3,4-tri-O-methyl-D-glucitol, 2,3,4-tri-O-methyl-D-galacitol 3,4,6-tri-O-methyl-galacitol, 2-O-methyl-arabinitol and 2,4,6-tri-O-methyl-D-glucitol, 2,3,6-tri-O-methyl-D-galacitol linkages, respectively.

Predegenerated peripheral nerve grafts rescue retinal ganglion cells from axotomy-induced death

The inability of axons to grow across damaged central nervous system tissue is a well-known consequence of injury to the brain and spinal cord of adult mammals. Our previous studies showed that predegenerated peripheral nerve grafts facilitate neurite outgrowth from the injured hippocampus and that this effect was particularly distinct when 7-, 28-, and 35-day-predegenerated nerve grafts were used. The purpose of the present study was to use the above method to induce and support the regrowth of injured nerve fibers as well as the survival of retinal ganglion cells (RGCs). Adult Sprague-Dawley rats were assigned to three groups. In the experimental groups transected optic nerve was grafted with peripheral nerve (predegenerated for 7 days (PD) or nonpredegenerated). In the control group, the optic nerve was totally transected. RGCs and growing fibers labeled with fluorescent tracers were examined. They were counted and the results were subjected to statistical analysis. Retinal ganglion cells survived in the groups treated with predegenerated as well as nonpredegenerated grafts; however, the number of surviving retinal ganglion cells was significantly higher in the first one. In both groups the regrowth of the transected optic nerve was observed but the distance covered by regenerating fibers was longer in the PD group. No fibers inside grafts and no labeled cells in retinas were present in the control animals. On the basis of the obtained results we can state that the predegeneration of grafts enhance their neurotrophic influence upon the injured retinal ganglion cells.

Neurotoxicity of soluble macrophage products in vitro--influence of dexamethasone

When macrophage conditioned medium is added to neurons in vitro, there is a loss of cell membrane integrity, a loss of cell processes, and a large increase in apoptotic neurons. We tested the influence of a potent anti-inflammatory steroid on the interaction between macrophages and neurons. Dexamethasone was applied to macrophages in culture for 24 h while the culture was stimulated with lipopolysaccharide and hypoxia. Conditioned medium was collected after dexamethasone was removed. The dexamethasone pretreated medium was not toxic to hippocampal neurons in contrast to medium from stimulated macrophages not treated with steroid. The dexamethasone effect was concentration dependent. Pretreatment of macrophages with indomethacin and transforming growth factor beta had similar but less impressive effects when compared to dexamethasone. The effect of dexamethasone may have been mediated by inhibiting the synthesis or release of neurotoxic macrophage protein(s), as a combination of medium from steroid pretreated macrophages with medium from nontreated macrophages was not neuroprotective. The toxin(s) did not appear to be tumor necrosis factor alpha or arginase. A role for most neutral proteases was also excluded. We also assessed the consequence of stressing neurons with a mild hypoxic exposure immediately prior to conditioned medium application. Medium from dexamethasone-treated macrophages did not exaggerate hypoxic neuronal injury, unlike medium from non-dexamethasone-treated macrophages. It did not, however, block the exaggerating effect when coapplied in equal volume with medium from nontreated macrophages. Dexamethasone at 100 nM had no impact when applied directly to neurons while they were being exposed to conditioned medium. This in vitro protection by dexamethasone may be relevant to the demonstrated benefit of glucocorticoids in selected brain and spinal cord conditions. Suspicion of a potential link between this in vitro finding and in vivo CNS injury justifies an assessment of more specific agents acting on macrophage protein synthesis or secretion.

Identification of a human dermal macrophage population responsible for constitutive restraint of primary dermal fibroblast proliferation

Primary human dermal cell suspensions prepared from the papillary dermis of keratomed skin strips were used to investigate the effect of indigenous dermal macrophages (HLA-DR+, CD11c+ CD11b+ CD1c- phagolysosome+) upon dermal fibroblast proliferation. Rapid dermal fibroblast expansion was induced upon immunomagnetic bead removal of CD11b+ or CD11c+ cells as well as by removal of more inclusive subsets contained within the DR+ population, but the removal of mast cells, endothelial cells, and CD1c+ dermal Langerhans cells from dermal cell suspensions failed to result in proliferation of the remaining cell subsets. Removal of 1B10+ fibroblasts from macrophage depleted (CD11b-) dermal cell suspensions essentially abrogated the unrestrained proliferation of the CD11b- dermal cells. Flow cytometric cell cycle analysis of cultured macrophage-depleted dermal cells confirmed that the unrestrained proliferating cells contain procollagen I+ as well as procollagen I- dermal fibroblasts. Inhibition of primary fibroblast expansion by adding a supernatant from unfractionated dermal cells suggested that a growth-inhibitory soluble activity of >30,000 kDa dominates the cytokine mixture released by unfractionated fresh dermal cells ex vivo. Inhibitory activity counterbalanced positive fibroblast growth- stimulatory cytokines released by dermal cells because neutralizing antibodies to insulin-like growth factor 1 and interleukin-1 beta resulted in decreased CD11b- dermal cell fibroblast proliferation. These data indicated an important role for dermal macrophages of the DR+ CD11b+ CD11c+ DC1c- phenotype in the normal homeostatic restraint of primary human dermal fibroblast proliferation.

The role of inflammatory mediators in the pathogenesis of periodontal disease

The role of bacteria in the initiation of periodontitis is well-documented and the end result, destruction of the alveolar bone and periodontal connective tissue, is readily observed; but the events occurring between these two points in time remain obscure and are the focus of this paper. Bacteria induce tissue destruction indirectly by activating host defense cells, which in turn produce and release mediators that stimulate the effectors of connective tissue breakdown. Components of microbial plaque have the capacity to induce the initial infiltrate of inflammatory cells including lymphocytes, macrophages, and PMNs. Microbial components, especially lipopolysaccharide (LPS), have the capacity to activate macrophages to synthesize and secrete a wide array of molecules including the cytokines interleukin-1 (IL-1) and tumor-necrosis factor-alpha (TNF-alpha), prostaglandins, especially PGE2, and hydrolytic enzymes. Likewise, bacterial substances activate T lymphocytes and they produce IL-1 and lymphotoxin (LT), a molecule having properties very similar to TNF-alpha. These cytokines manifest potent proinflammatory and catabolic activities, and play key roles in periodontal tissue breakdown. They induce fibroblasts and macrophages to produce neutral metalloproteinases such as procollagenase and prostromelysin, the serine proteinase urokinase-type plasminogen activator (u-PA), tissue inhibitor of metalloproteinase (TIMP), and prostaglandins, u-PA converts plasminogen into plasmin, which can activate neutral metalloproteinase proenzymes, and these enzymes degrade the extracellular matrix components. TIMP inactivates the active enzymes and thereby blocks further tissue degradation. Several amplification and suppression mechanisms are involved in the process. While LPS activates macrophages to produce IL-1, IL-1 is autostimulatory and can therefore amplify and perpetuate its own production. Interferon-gamma (INF-gamma) suppresses autostimulation, but it enhances LPS-induced IL-1 production. PGE2 exerts a control over the whole process by suppressing production of both IL-1 and TNF-alpha. Furthermore, the activated cells produce an IL-1 receptor antagonist that binds to the IL-1 receptor but does not induce the biologic consequences of IL-1 binding. Other cytokines such as transforming growth factor-beta (TGF-beta) suppress production of metalloproteinases and u-PA. Thus the progression and extent of tissue degradation is likely to be determined in major part by relative concentrations and half-life of IL-1, TNF-alpha, and related cytokines, competing molecules such as the IL-1 receptor antagonist, and suppressive molecules such as TGF-beta and PGE2. These molecules control levels of latent and active metalloproteinase and u-PA, and the availability and concentration of TIMP determines the extent and duration of degradative activity.

In vivo degradation of oxidized, regenerated cellulose

Oxidized, regenerated cellulose (ORC) was surgically implanted on the uterine horns of rabbits, and its biodegradation was studied in vivo. Samples of peritoneal lavages, serum, and urine were collected during the degradation process and analyzed for carbohydrate components utilizing high-performance liquid chromatography with pulsed amperometric detection (h.p.l.c.-p.a.d.). Degradation was rapid, and oligomeric products were evident primarily in the peritoneal fluid from the implantation site, with no apparent accumulation in either the serum or the urine. The size distribution and the amount of the oligomeric products decreased after day one, and by day four peritoneal lavages were essentially free of oligomers. The structure of the products formed was consistent with the lability of the polymer in solution, and the kinetics of degradation paralleled the results of the previously reported in vitro studies. Rabbit peritoneal macrophages, when incubated with ORC in vitro were observed to readily ingest and hydrolyze the polymeric material. A mechanism of degradation consisting of chemical depolymerization, followed by enzymatic hydrolysis mediated by glycosidases endogenous to peritoneal macrophages, is proposed.

Effects of blood monocytes and lymphocytes on progesterone secretion by granulosa cells in the pig

We studied the effects of autologous and nonautologous co-cultures of porcine blood monocytes and lymphocytes with granulosa cells on progesterone secretion. Eight prepubertal crossbred gilts were ovariectomized, and the granulosa cells were collected, plated at 2.5 x 10(5) cells/ml and allowed to attach. Blood was obtained from the same eight gilts, and the mononuclear cells were separated by density gradient centrifugation. Monocytes were separated from lymphocytes by adherence to plastic. Adherent monocytes, lymphocytes and a 1:1 mixture of monocytes + lymphocytes were added to granulosa cell cultures and incubated for 48 h. Progesterone secretion into the media was measured. In addition, blood cell alloreactivity was studied in these co-cultures by measuring uptake of (3)H-thymidine. The co-culture of adherent monocytes or monocytes + lymphocytes with granulosa cells increased (P <.05) progesterone secretion as compared with granulosa cells cultured alone. However, co-culture of lymphocytes with granulosa cells did not have a significant effect. No difference was observed between autologous and nonautologous cell cultures in blood cell proliferation or granulosa cell progesterone secretion. In conclusion, blood monocytes influence progesterone secretion by granulosa cells. In addition, there was no difference in the ability of autologous and nonautologous blood cells to stimulate progesterone secretion by granulosa cells. No alloreactivity was observed using nonautologous immune cells with granulosa cells.

Prostaglandin H synthase immunoreactivity localized by immunoperoxidase technique (PAP) in the small intestine and kidney of rabbit and guinea-pig

Prostaglandins and inhibitors of prostaglandin synthesis have striking regulatory effects on intestinal muscularis externa. We suggested earlier that a population of macrophage-like cells, located between the external muscle layers might release prostaglandins with a local effect on enveloping interstitial cells of Cajal, postulated pacemaker cells of the gut. To determine cellular production site(s) of prostaglandin we applied monoclonal antibodies against prostaglandin H synthase combined with the PAP technique to sections of rabbit and guinea-pig small intestine and kidney. In rabbit small intestine muscle cells in the circular muscle layer and in the muscularis mucosae were positive, longitudinal muscle negative. Vascular endothelial cells and serosal mesothelial cells were stained. In guinea-pig all muscle layers were unstained but endothelial and mesothelial cells were stained together with unidentified cells in the outermost submucosa. In rabbit kidney, positive staining of collecting ducts, interstitial cells, the parietal layer of Bowman's capsule and arterial endothelial cells was present. Furthermore, we found prostaglandin synthase antigenicity in the epithelial cells lining the loop of Henle, not described before. In guinea-pig medullary collecting ducts were stained and the papilla was lined by stained epithelial cells. The results show a species variation in the distribution of recognizable levels of prostaglandin H synthase. The impressive reaction in the mesothelium must be considered, when enzyme distribution is examined biochemically with fractionated tissue. Our findings do not support our hypothesis that macrophage-like cells are more potent sources of prostaglandins than smooth muscle cells.

Cytotoxic effector cells of the immune system

The organism contains several types of cytotoxic cells which are able to lyse host and foreign cells. Cytotoxic T-lymphocytes (CTL) appear to play the most important role among the killer cells but other lymphatic cells, such as natural killer (NK) cells and lymphokine-activated killer (LAK) cells as well as macrophages are also highly effective in the lysis of appropriate targets. The various cytotoxic effector cells differ distinctly concerning origin, phenotype, morphology and target cell specificity, but they bear the common feature that they destroy the target cells in a contact-dependent non-phagocytotic process. CTL are characterized by typical lysosomal granules and by the expression of a characteristic pattern of surface molecules. They recognize specific antigens which are presented in context with molecules of class I major histocompatibility complex (MHC). NK cells, on the other hand, kill the appropriate targets without prior immunisation and without requiring recognition of MHC molecules at the target cells. They also bear a typical pattern of surface markers which differ in several aspects from that of CTL. Human NK cells are further characterized by peculiar cytoplasmic granules with parallel tubular arrays which are not present in other cytotoxic cells. LAK cells constitute an additional, only recently described, killer cell population which arise from lymphatic cells in the presence of interleukin-2. They appear to represent a functional unique cytotoxic effector cell system with an exceptionally wide target cell spectrum including normal and malignant cells of different origin. LAK cells, however, show a profound heterogeneity concerning the expression of phenotype surface markers and it is not yet clear whether they are a unique cell line. By electron microscopy they display peculiar intranuclear inclusion bodies which may be associated with prolonged stimulation by interleukin-2. CTL, NK and LAK cells appear to possess similar mechanisms for cytolysis including secretion of pore-forming proteins, serine proteases and other proteins. Furthermore, they are able to trigger the cleavage of DNA in the target cell nucleus by a hitherto unknown pathway. Macrophages differ substantially from other cytotoxic effector cells concerning morphology, phenotype, kinetic of activation and target cell spectrum. They perform a variety of functions whereby contact-dependent target cell lysis represents only one of their properties. After target cell binding they release over 20 different molecules such as interleukin-1 and tumor necrosis-factor-alpha as mediators for cytolysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Vascular smooth muscle phenotype and growth behaviour can be influenced by macrophages in vitro

The effect of macrophages on rabbit vascular smooth muscle phenotype and proliferative ability was examined using ultrastructural morphometry. The volume fraction of myofilaments (Vv myo) in smooth muscle cells (SMC) from 9-week-old rabbit aorta in vivo was 39.5 +/- 1.2%. After seeding the enzymatically isolated SMC at 4 X 10(5) cells/ml in primary culture, the Vv myo was 38.9 +/- 1.2% on day 3 dropping to 29.9 +/- 2.0% by day 5. On day 6 the Vv myo was 29.2 +/- 1.8%, and the cells began to proliferate. Confluency was reached after less than 24 h proliferation and the Vv myo rose abruptly on day 7 to 36.9 +/- 1.9%. When the SMC were co-cultured with macrophages, the Vv myo fell to 31.2 +/- 0.9% on day 3 and to 25.9 +/- 0.5% on day 5 at which time cells commenced proliferation. Confluency occurred on day 6 but the SMC Vv myo did not rise throughout the rest of the culture period (27.4 +/- 1.8% and 26.9 +/- 1.3% on days 7 and 9, respectively) and the cells, unlike the controls, continued to proliferate, becoming multi-layered. Early phenotypic modulation in sparsely seeded SMC (8 X 10(4) cells/ml) co-cultured with macrophages was also found using fluorescent labelled antibodies to smooth muscle myosin. Measurement of proliferation by cell counts (and tritiated thymidine autoradiography) showed that macrophages stimulated SMC in primary culture to proliferate at a significantly greater rate than control cells grown alone in 5% whole blood serum (WBS). Proliferation of subcultured SMC co-cultured with macrophages was also stimulated.(ABSTRACT TRUNCATED AT 250 WORDS)

Macrophage-mediated myelin-related mitogenic factor for cultured Schwann cells

Conditioned medium from cultured peritoneal macrophages that have phagocytosed a myelin membrane fraction is mitogenic for cultured Schwann cells. Production of the mitogenic supernatant was time- and dose-dependent with a maximal Schwann cell-proliferative response from supernatants after 48-hr incubation of cultured macrophages with myelin-enriched fraction (200 micrograms of protein per ml). The response was specific for myelin membrane: supernatants derived from macrophages incubated with axolemma, liver microsomes, polystyrene beads, or lipopolysaccharide were not mitogenic. Lysosomal processing of the myelin membrane was necessary for the production of the mitogenic factor, which was shown to be heat labile and trypsin sensitive. There was no species specificity because myelin membranes isolated from the central and peripheral nervous systems of rat, bovine, and human were equally potent in eliciting mitogenic supernatant. However, supernatants derived from central nervous system myelin membranes were two to three times more mitogenic than those obtained from peripheral nervous system fractions of the same species. Previous observations that myelin is mitogenic for cultured Schwann cells may, in part, involve the intermediate processing of myelin by macrophages that are present in Schwann cell cultures. These results suggest that macrophages play a crucial role in Schwann cell proliferation during Wallerian degeneration.

Secreted proteins of human monocytes. Analysis by two-dimensional gel electrophoresis and effect of lipopolysaccharide

A monocyte-rich preparation from the adherent cell fraction of human peripheral blood leukocytes was incubated for 1-8 h with [35S]methionine or [3H]leucine in the presence and absence of bacterial lipopolysaccharide (LPS). The macromolecules released into the supernatant were analysed by two-dimensional gel electrophoresis and radioautography. A complex labelling pattern involving at least 20 easily demonstrable and apparently distinct products with a broad range of molecular masses and isoelectric points was observed. LPS or LPS plus actinomycin in combination markedly stimulated the labelling and release of at least twelve different macromolecules ranging in apparent Mr from 12,000 to 46,000. Studies with monocytes that had been additionally purified by centrifugal elutriation and with the monocyte-like human cell line U-937 indicated that monocytes rather than contaminating cells were the source of these products. The majority of the secreted products were unique and did not cross-react with antibodies to interleukin 1 or tumour necrosis factor. The high resolving capacity of two-dimensional gel electrophoresis may be useful to define further the diverse biological activities and potential monokines released from monocytes at various stages of their differentiation and activation.

Lysosomal enzymes in bovine mammary leukocytes during the nonlactating period

Leukocytes from mammary secretions in dairy cows were collected during the nonlactating and postpartum periods. Differential cell counts, viability and activity of peroxidase, N-acetyl-beta-D-glucosaminidase (NAGase, beta-glucuronidase and alpha-mannosidase in cells were determined. Cell viability (trypan blue exclusion) was 75-80% during most of the nonlactating period, but declined to 45-50% by parturition. Polymorphonuclear neutrophils (PMN) predominated during the first week of involution, after which macrophages were the predominant cell type. Peroxidase activity in leukocytes from mammary secretions was high in early involution, probably reflecting the predominant peroxidase-containing PMN. Peroxidase activity declined through the remaining nonlactating and postpartum periods. The activity of NAGase was variable in early involution, then increased to a peak during the mid-nonlactating period, before declining prior to parturition. Activity of beta-glucuronidase generally was unchanged during the nonlactating period, although NAGase and beta-glucuronidase activities were significantly and positively correlated throughout the period studied. Activity of alpha-mannosidase changed in a manner similar to peroxidase activity.

Stimulation of complement component C3 synthesis in macrophagelike cell lines by group B streptococci

Complement levels and complement activation are key determinants in streptococcus-induced inflammatory responses. Activation of macrophage functions, such as complement synthesis, by group B streptococci (GBS) was examined as a possible component of GBS-induced chronic inflammation. Using an enzyme-linked immunosorbent assay, secreted C3 from mouse macrophagelike cell lines (PU5-1.8 and J774A.1) was monitored after cultivation with GBS. Whole, heat-killed GBS (1 to 10 CFU per macrophage) of both type Ia and III strains induced 25 to 300% increases in secreted C3 in both cell lines after a 24-h cultivation. GBS-treated cell lines exhibited increases in secreted lysozyme (10%) and in cellular protein (25 to 50%). Inhibition of macrophage phagocytosis by cytochalasin B inhibited GBS stimulation of C3. Purified cell walls of GBS type III strain 603-79 (1 to 10 micrograms/ml) also enhanced C3 synthesis. Local enhancement of macrophage C3 production by ingested streptococci or by persistent cell wall antigens may serve to promote chronic inflammatory responses.

Mouse peritoneal macrophages cultured serum-free deposit complement on IgM-coated sheep erythrocytes in vitro

We conclude that the macrophages during cultivation produce the complement components of the classical pathway of complement, deposit complement components on EIgM and then phagocytose these cells via complement receptors. The conclusion is based on the following: EIgM, an activator of the classical pathway, are ingested when cultured serum-free with mouse peritoneal macrophages. We found a significantly higher binding of labelled protein to EIgM than to E kept in macrophage cultures in the presence of tritiated leucine, showing that de novo synthesis of macrophage-derived protein with affinity to EIgM takes place. A fraction of the bound protein is C3b and iC3b, since anti-mouse C3 antibodies bound to the co-cultured EIgM. Cycloheximide or anti-Mac-1 in the cultures inhibited macrophage attachment and uptake of EIgM. The phagocyte uptake of EIgM coated with complement by serum pretreatment was not inhibited by cycloheximide. This shows that the phagocytosis of the EIgM is dependent on erythrocyte-bound complement proteins made by the macrophage.

Intravascular macrophages in lungs of pigs infected with Haemophilus pleuropneumoniae

Pigs were inoculated intratracheally with a virulent or an avirulent isolate of Haemophilus pleuropneumoniae serotype 5 and sacrificed during the first 24 hours post-inoculation. Intravascular macrophages were examined by electron microscopic and morphometric techniques. Samples of lung were taken from regions with no macroscopic lesions (Zone 0), 2.5 to 3.0 cm from lesions (Zone 1), and from the immediate edge of lesions (Zone 2). Those pigs inoculated with the avirulent isolate did not develop lesions. Pigs given the virulent isolate consistently developed necrohemorrhagic lesions in the dorsolateral aspect of the caudal and middle lung lobes. Relative volumes of intravascular macrophages in Zones 1 and 2 increased with increased time post-inoculation; in pigs given the avirulent isolate, intravascular macrophage volume decreased with increased time post-inoculation. Cytoplasmic volume to nuclear volume ratios for macrophages in Zone 2 from pigs with necrohemorrhagic lesions progressively increased with increased time post-inoculation. Enlarged intravascular macrophages had large nuclei, prominent nucleoli, and abundant cytoplasm. Increased cytoplasmic volume was the result of increased numbers of lysosomes, phagosomes, rough and smooth endoplasmic reticulum, and large Golgi complexes. Pigs inoculated with the virulent bacteria had IV macrophages with large phagosomes that contained necrotic cell debris and fibrin. Macrophages with phagosomes were more frequent in the 6-, 9-, and 24-hour sample periods of pigs with lesions than in any other group. Intercellular adhesion plaques (ICAP) were present between IV macrophages and subjacent endothelial cells. ICAP's increased in length with increased time post-inoculation in Zones 1 and 2 from pigs with necrohemorrhagic lesions. In later sample periods, multiple closely associated and interlacing IV macrophages formed a discontinuous layer over endothelial cells in Zone 2 samples near necrohemorrhagic lesions. These results suggest that the intravascular macrophage population changes from immature macrophages to mature macrophages or immature epithelioid cells within 24 hours after inhalation of a virulent Haemophilus pleuropneumoniae. Furthermore, intravascular macrophages likely function to clear cellular and acellular debris from the blood in pneumonic conditions.

Is Reye's syndrome caused by augmented release of tumour necrosis factor?

Reye's syndrome affects children with a history of viral infection treated with aspirin. Its pathogenesis is unclear. Tumour necrosis factor (TNF) is released by macrophages activated by viral infection, endotoxin, and phagocytosis, and it has been shown to be a mediator of the toxic and metabolic effects of endotoxaemia. The metabolic effects of endotoxin and TNF are similar to those found in Reye's syndrome. Raised levels of TNF are released from macrophages treated with non-steroidal anti-inflammatory drugs, and young animals are known to be more sensitive than mature animals to both TNF and endotoxin. These observations lead to the hypothesis that an increased release of TNF in selected young patients treated with aspirin contributes to the development of Reye's syndrome.

Molecular forms of myeloperoxidase in human plasma

A radioimmunoassay for myeloperoxidase was established with the use of affinity-purified anti-(human myeloperoxidase) immunoglobulins. By the use of ion-exchange followed by immunoaffinity chromatography a preparation of immunoreactive, catalytically active myeloperoxidase was obtained from fresh human plasma. In non-denaturing gel electrophoresis, the plasma preparation showed about four catalytically active components of mobility very similar to that of the granulocyte enzyme. SDS/polyacrylamide-gel electrophoresis combined with protein blotting showed that the two polypeptides of strongest antigenicity in the plasma preparation corresponded in Mr to the large and the small subunits of the granulocyte enzyme. In addition, the plasma preparation contained a higher-Mr immunoreactive polypeptide, possibly a precursor form of the enzyme, together with another of Mr similar to that of the large subunit of eosinophil peroxidase.

Suppression of fibroblast proliferation by activated macrophages: involvement of H2O2 and a non-prostaglandin E product of the cyclooxygenase pathway

Macrophages are considered promoters of fibroblast proliferation; however, suppression by activated macrophages may outweigh this effect. Activated murine peritoneal macrophages obtained by in vivo exposure to C. parvum or by in vitro LPS-activation of thioglycollate-induced macrophages, were tested for their effect on normal syngeneic dermal fibroblasts. C. parvum-activated macrophages, but not resident peritoneal macrophages suppressed fibroblast proliferation. Similarly, macrophages activated in vitro by LPS, but not those unexposed to LPS, suppressed fibroblast proliferation. Catalase partially protected fibroblasts from suppression by either activated macrophage population, suggesting involvement of H2O2 in the suppression. The effect of cyclooxygenase inhibitors on the suppression was also tested. Indomethacin, acetylsalicyclic acid, or eicosatetraynoic acid, all partially protected the fibroblasts from macrophage-mediated suppression. Prostaglandins E2, E1, and F2 alpha, added exogenously at concentrations as high as 10(-6) M, failed to suppress the proliferation of the fibroblasts. These findings suggest that a non-prostaglandin product of the cyclooxygenase pathway is involved in macrophage-mediated suppression of fibroblast proliferation.

Connective tissue as an integral system: role of cell-cell and cell-matrix interactions

We have applied the systems approach, to the analysis of mechanisms whereby connective tissue (CT) is integrated into one functional system. The primary CT functions in health and in disease (biomechanical, trophic, protective, reparative, and morphogenetic) are carried out by means of cell-cell, cell-matrix and intertissue interactions based on feedback between these components. Both CT as a whole and its cellular and extracellular elements exhibit structural and functional heterogeneity which increases the capacity of CT for adaptation. The intercellular interactions take place via soluble and insoluble mediators, direct cellular contacts, and cell/matrix degradation products. Results of this study support the concept of internal "network" regulation of the CT composition, functions and growth through intercellular interactions at different structural levels. Feedback mechanisms between degradation and production of collagen and interactions between collagen, macrophages and fibroblasts play a special role in the self-regulation of reparative CT growth. Collagen restores an impaired self-regulation and exerts a marked therapeutic effect on wounds, burns, trophic ulcers, and other lesions. A similar function may be performed by other matrix components and degradation/secretion products of macrophages and fibroblasts.

Identification of new collagen formation with 125I-labeled antibody in bovine pericardial tissue valves implanted in calves

Failure of bovine pericardial tissue valve used in young patients may be due to a slow rejection process. Polyclonal anticollagen (Type I) antibody (IgG) was made in rabbits and purified by protein A affinity column. Two milligrams of IgG was labeled with 2 mCi of 125I by the Iodogen method. Free iodide was separated by G-10 column. Affinity of 125I-IgG was checked by radioimmunoassay. Two hundred and fifty microcuries of 125I-IgG was injected in calves immediately after tissue valve implantation, and the calves were killed 4 h post-injection. After harvesting the valve, each of the three leaflets was separated into four zones, and radioactivity in each section was mapped with a gamma counter. The radioactivity in tissue valve section was compared to that of normal aortic valve. The sections of tissue valve retain five to ten times more 125I-IgG than control aortic valve. Iodine-IgG thus provides a sensitive technique for determination of residual antigenicity in tissue valve.

Immunohistochemical demonstration of S-100 protein antigen-containing cells in chronic cutaneous leishmaniasis

The presence and distribution of S-100 protein antigen and lysozyme were investigated by the immunoperoxidase method in paraffin sections of 13 cases of chronic cutaneous leishmaniasis from Saudi Arabia. Varying numbers of S-100+lys- histiocytic reticulum cells were found in the dense inflammatory infiltrate in 11 out of 13 cases. These cells were considerably more numerous in the lesions dominated by cells of the mononuclear phagocytic system and granulomata than in the cases with plasma cellular or lymphocytic predominance. Activated lys+ macrophages, epithelioid cells, and multinucleated giant cells were always S-100-. Around the granulomata several S-100+lys- histiocytic reticulum cells could be found. These findings suggest that antigen-presenting cells are present in the inflammatory infiltrate of cutaneous leishmaniasis.

Macrophage-like cells in the muscularis externa of mouse small intestine

In muscularis externa of mouse small intestine, cells with ultrastructural features of macrophages were invariably observed in three layers: in the subserosal layer, between the circular and longitudinal muscle layers, and in association with the deep circular plexus. These macrophage-like cells (MLC) had a single indented nucleus, perinuclear Golgi complex, smooth and rough endoplasmic reticulum, many pits (coated and uncoated) in the plasma membrane, coated vesicles, light vesicles, and primary lysosomes, but rather few heterogeneous lysosomal vacuoles. MLC were partially enveloped by processes of interstitial cells of Cajal. FITC-dextran used in combined fluorescence stereo microscopy, fluorescence microscopy, and electron microscopy was employed as a tracer to study the endocytic qualities of the MLC. The mice were killed 5, 15, 30, and 60 min, 1 day, and 4 days after dextran administration. By fluorescence microscopy after 1 or 4 days MLC were observed as a constant cellular population with a strikingly regular distribution. By electron microscopy dextran-containing vacuoles were conspicuous after 1 h or more. MLC of the subserosal layer and between the circular and longitudinal muscle layers could be distinguished with respect to general appearance, pattern formation, and apparent dextran contents.

The influence of murine macrophage-conditioned medium on cloning efficiency, antibody synthesis, and growth rate of hybridomas

Murine B-cell hybridomas made with the P3X63-AG8.653 myeloma showed increases in cloning efficiency and efficiency of growth in hypoxanthine-aminopterin-thymidine (HAT) medium of 50-100-fold in the presence of medium conditioned by primary mouse peritoneal macrophages (MCM). Similar effects were elicited by MCM from 3 continuous macrophage lines. The J774A.1 line conditioned the medium as efficiently as primary macrophages without induction. Conditioning by the P388D1 line was several-fold less efficient, but could be increased by treating the cells with Escherichia coli lipopolysaccharide. By contrast, the BJ-1 macrophage line required treatment with the lipopolysaccharide to induce expression of the hybridoma growth factor(s). Four commercially available serum supplements could not substitute for MCM, but addition of MCM and the supplements together stimulated the growth rate of hybridomas in media with 4% or less fetal bovine serum. The rate of antibody synthesis paralleled the growth rate, and the amount of antibody synthesized per cell was approximately the same for hybridomas grown in medium supplemented with MCM or adapted to growth in the absence of MCM. The results indicate that MCM has advantages as an alternative to 'feeder cells' and serum supplements in hybridoma cultures, and suggest that MCM may be useful for hybridoma culture at reduced serum concentrations. The nature of the soluble factor(s) in MCM which promote these effects remains unknown.

[1-14C]Arachidonic acid incorporation into glycerolipids and prostaglandin synthesis in peritoneal macrophages: effect of chloramphenicol

Peritoneal macrophages from normal mice were labelled with [1-14C]arachidonic acid after 2 h culture. The uptake of arachidonic acid into cellular lipids was rapid, time-dependent and can be represented within the limit of the studied times by a parabolic regression. Indomethacin decreased the kinetics of uptake; this inhibition is dose-dependent. Chloramphenicol had no effect on macrophage [1-14C]arachidonic acid uptake. After 3 h, the radioactivity was recovered in phosphatidylcholine (38.6%), phosphatidylserine-phosphatidylinositol (8.5%), phosphatidylethanolamine (22.1%), diacylglycerol (2.9%), triacyglycerol (2%) and cholesteryl ester (11.8%). Chloramphenicol and indomethacin inhibited the labelling of phospholipids and stimulated the labelling of neutral lipids and cholesteryl ester. Studies on arachidonic acid release from glycerolipids of prelabelled 2-h cultured macrophages showed that phosphatidylcholine and phosphatidylserine-phosphatidylinositol are the major source of arachidonic acid in prostaglandin synthesis in macrophages stimulated or not by zymosan. Chloramphenicol inhibited release of fatty acid from phosphatidylcholine and phosphatidylserine-phosphatidylinositol; indomethacin had no effect. Both drugs inhibited prostaglandin synthesis in stimulated or non-stimulated macrophages. In the culture medium, indomethacin increased the release of free arachidonic acid by stimulated macrophages. Possible explanations for the mechanisms underlying these effects are presented. It is concluded that indomethacin and chloramphenicol exert profound effects on the metabolism of phospholipids and its zymosan activation. Chloramphenicol appears to impair prostaglandin synthesis through several mechanisms and especially through phospholipase inhibition.

Immunoreactive fibroblast growth factor in cells of peritoneal exudate suggests its identity with macrophage-derived growth factor

Peritoneal exudate cells were collected from thioglycollate stimulated mice, extracted an examined for the presence of immunoreactive and bioactive fibroblast growth factor (FGF). The crude extract stimulated in a dose dependent fashion the proliferation of vascular endothelial cells derived from the bovine aortic arch. The extract also showed a parallel and dose-dependent inhibition of binding in a highly specific radioimmunoassay for FGF. The immunoreactive FGF (ir-FGF) contained in the extract was retained on a heparin-sepharose affinity column as is characteristic of pituitary FGF. Reverse-phase HPLC of the macrophage-derived material reveals one biologically active form of FGF which coelutes with the major form of immunoreactivity. The results demonstrate the presence of FGF in these cells and suggest that at least one of the hitherto unidentified mitotic activities in these extracts is due to a mitogen indistinguishable from FGF.

Lectins modulate prostaglandin E2 production by rat peritoneal macrophages

The effect of Aloctin A (Alo A), a lectin having anti-inflammatory activities, on prostaglandin (PG) E2 production by activated rat peritoneal macrophages was compared with that of concanavalin A (Con A), wheat germ agglutinin (WGA), plsum sativum agglutinin (PSA) and soybean agglutinin (SBA). Alo A, WGA, Con A and PSA at 10 micrograms per ml inhibited PG E2 production. But SBA, even at a dose of 1 microgram per ml, stimulated PG E2 production. The inhibition by Alo A treatment of the release of radioactivity from (3H)arachidonic acid-labeled macrophages and the stimulation of this release by SBA treatment were observed. The uptake of (51Cr)-labeled sheep red blood cells by the macrophage was inhibited by Alo A, Con A, and PSA, all at 10 micrograms per ml and SBA at 1 microgram per ml, however, WGA at 10 micrograms per ml stimulated the uptake of the sheep red blood cells. The mechanism of the anti-inflammatory properties of Alo A was discussed.

Influence of a reticuloendothelial-suppressing agent on liver tumor growth in the rat

Reticuloendothelial (RE) function was evaluated by measuring the biokinetics of a standardized 99Tcm-sulphur colloid. Methyl palmitate was administered intravenously on two consecutive days. A statistically significant reduction in the colloid uptake rate of the liver was registered after methyl palmitate administration. Histological examination revealed no signs of destruction of RE cells or microembolization. Inoculation of an experimental nitrosoguanidine-induced transplantable adenocarcinoma to the liver was performed in 16 rats one day after methyl palmitate administration and in 16 controls. Tumor size was significantly larger in methyl-palmitate-treated animals at 7 and 14 days after inoculation. Survival was significantly decreased in methyl-palmitate-treated rats. These rats showed signs of fatty vacuolization and necrosis of liver parenchyma earlier than controls. Analyses of beta-hexosaminidase and lactate dehydrogenase revealed no deviation of enzyme levels either before or after tumor inoculation. The results indicate that a temporary suppression of RE function at the time of tumor inoculation may influence subsequent tumor growth.

Role of protein synthesis in the activation of cytotoxic mouse macrophages by lymphokines

The role of protein synthesis during the activation of macrophages (M phi) by lymphokines (LK) was studied. Peritoneal murine macrophages elicited by proteose-peptone (pM phi) were activated with LK (supernatants from normal mouse spleen cells pulsed with concanavalin A) and tested for cytotoxicity in an 18 hr assay against 111In-labeled L5178Y lymphoma target cells. Reversible (cycloheximide and puromycin) or poorly reversible (emetine and pactamycin) inhibitors of protein synthesis were added during activation, and their effects on pM phi-mediated cytotoxicity and pM phi protein synthesis were measured. Minimal concentrations of inhibitors, reducing the rate of protein synthesis by more than 90% without toxic effects on macrophages, were chosen. Exposure of pM phi to LK for 2 to 18 hr in the presence of reversible inhibitors of protein synthesis did not affect the induction of cytolytic activity, indicating that protein synthesis was not required during the activation period. In contrast, activation of macrophages for 2 hr in the presence of poorly reversible inhibitors of protein synthesis resulted in a considerable reduction of cytolytic activity. The impairment of cytotoxic activity was also evident when pM phi were treated with such drugs during the first 2 hr of an 18 hr exposure to LK or when LK-activated macrophages were treated for 2 hr with the drugs before the addition of the targets. These results demonstrate that active protein synthesis is not required during the exposure of pM phi to LK, but that new proteins have to be synthesized to allow the expression of the cytotoxic activity in LK-activated pM phi.

Lymphokines inhibit macrophage RNA synthesis

The effects of lymphokine (LK) preparations on the incorporation of [3H]uridine into macrophage RNA were investigated. Supernatants from murine spleen cells activated in vitro by alloantigens or Con A, and shown to contain macrophage-activating factor (MAF), were used as the source of LK. It was observed that such LK preparations contain factor(s) causing a profound inhibition of [3H]uridine incorporation into the RNA of proteose-peptone-elicited peritoneal macrophages. Such RNA-labeling inhibitory factor (RIF) was absent in control supernatants from nonstimulated cultures, and showed activation curves similar to that of MAF. RIF activity was not due to altered permeability of macrophages to [3H]uridine nor to the changes in the specific activity of the pool of RNA precursors, but rather reflected an altered metabolism of RNA. The inhibition of RNA synthesis was dependent upon the presence of nanogram amounts of LPS as a costimulator. Moreover, the response to RIF appeared to be genetically controlled since macrophages from C3H/HeJ mice were not affected by RIF, while C3H/HeN mice were fully responsive. In parallel cultures of macrophages, LK were also tested for their MAF activity, and a strong similarity between the biological conditions in which MAF and RIF activities were expressed could be demonstrated. The assay for RIF provides a new and convenient parameter for measuring macrophage-sensitive LK activity that might be very useful for monitoring purification or for screening of T-cell hybridoma supernatants.