A histochemical study of phagocytic and enzymatic functions of rabbit mononuclear and polymorphonuclear exudate cells and alveolar macrophages. I. Survey and quantitation of enzymes, and states of cellular activation

Poly(malic acid)-budesonide nanoconjugates embedded in microparticles for lung administration

To improve the therapeutic activity of inhaled glucocorticoids and reduce potential side effects, we designed a formulation combining the advantages of nanoparticles, which have an enhanced uptake by alveolar cells, allow targeted delivery and sustained drug release, as well as limited drug systemic passage, with those of microparticles, which display good alveolar deposition. Herein, a polymer-drug conjugate, poly(malic acid)-budesonide (PMAB), was first synthesized with either 11, 20, 33, or 43 mol% budesonide (drug:polymer from 1:8 to 3:4), the drug creating hydrophobic domains. The obtained conjugates self-assemble into nanoconjugates in water, yielding excellent drug loading of up to 73 wt%, with 80-100 nm diameters. In vitro assays showed that budesonide could be steadily released from the nanoconjugates, and the anti-inflammatory activity was preserved, as evidenced by reduced cytokine production in LPS-activated RAW 264.7 macrophages. Nanoconjugates were then embedded into microparticles through spray-drying with L-leucine, forming nano-embedded microparticles (NEMs). NEMs were produced with an aerodynamic diameter close to 1 µm and a density below 0.1 g.cm-3, indicative of a high alveolar deposition. NEMs spray-dried with the less hydrophobic nanoconjugates, PMAB 1:4, were readily dissolved in simulated lung fluid and were chosen for in vivo experiments to study pharmacokinetics in healthy rats. As it was released in vivo from NEMs, sustained distribution of budesonide was obtained for 48 h in lung tissue, cells, and lining fluid. With high loading rates, modulable release kinetics, and low cytotoxicity, these nanoconjugates delivered by NEMs are promising for the more efficient treatment of pulmonary inflammatory diseases.

Perspectives for Developing New Tuberculosis Vaccines Derived from the Pathogenesis of Tuberculosis: I. Basic Principles, II. Preclinical Testing, and III. Clinical Testing

Part I. Basic Principles. TB vaccines cannot prevent establishment of the infection. They can only prevent an early pulmonary tubercle from developing into clinical disease. A more effective new vaccine should optimize both cell-mediated immunity (CMI) and delayed-type hypersensitivity (DTH) better than any existing vaccine. The rabbit is the only laboratory animal in which all aspects of the human disease can be reproduced: namely, the prevention of most primary tubercles, the arrestment of most primary tubercles, the formation of the tubercle’s solid caseous center, the liquefaction of this center, the formation of cavities and the bronchial spread of the disease. In liquefied caseum, virulent tubercle bacilli can multiply extracellularly, especially in the liquefied caseum next to the inner wall of a cavity where oxygen is plentiful. The bacilli in liquefied caseum cannot be reached by the increased number of activated macrophages produced by TB vaccines. Therefore, new TB vaccines will have little or no effect on the extracellular bacillary growth within liquefied caseum. TB vaccines can only increase the host’s ability to stop the development of new TB lesions that arise from the bronchial spread of tubercle bacilli from the cavity to other parts of the lung. Therefore, effective TB vaccines do not prevent the reactivation of latent TB. Such vaccines only control (or reduce) the number of metastatic lesions that result after the primary TB lesion was reactivated by the liquefaction process. (Note: the large number of tubercle bacilli growing extracellularly in liquefied caseum gives rise to mutations that enable antimicrobial resistance—which is a major reason why TB still exists today). Part II. Preclinical Testing. The counting of grossly visible tubercles in the lungs of rabbits after the inhalation of virulent human-type tubercle bacilli is the most pertinent preclinical method to assess the efficacy of new TB vaccines (because an effective vaccine will stop the growth of developing tubercles before while they are still microscopic in size). Unfortunately, rabbits are rarely used in preclinical vaccine trials, despite their relative ease of handling and human-like response to this infection. Mice do not generate an effective DTH response, and guinea pigs do not generate an effective CMI response. Only the rabbits and most humans can establish the proper amount of DTH and CMI that is necessary to contain this infection. Therefore, rabbits should be included in all pre-clinical testing of new TB vaccines. New drugs (and/or immunological procedures) to reduce liquefaction and cavity formation are urgently needed. A simple intradermal way to select such drugs or procedures is described herein. Part III. Clinical Testing. Vaccine trials would be much more precise if the variations in human populations (listed herein) were taken into consideration. BCG and successful new TB vaccines should always increase host resistance to TB in naive subjects. This is a basic immunological principle. The efficacies of new and old TB vaccines are often not recognized, because these variations were not identified in the populations evaluated.

Human lung hydrolases delineate Mycobacterium tuberculosis-macrophage interactions and the capacity to control infection

Pulmonary surfactant contains homeostatic and antimicrobial hydrolases. When Mycobacterium tuberculosis is initially deposited in the terminal bronchioles and alveoli, as well as following release from lysed macrophages, bacilli are in intimate contact with these lung surfactant hydrolases. We identified and measured several hydrolases in human alveolar lining fluid and lung tissue that, at their physiological concentrations, dramatically modified the M. tuberculosis cell envelope. Independent of their action time (15 min to 12 h), the effects of the hydrolases on the M. tuberculosis cell envelope resulted in a significant decrease (60-80%) in M. tuberculosis association with, and intracellular growth of the bacteria within, human macrophages. The cell envelope-modifying effects of the hydrolases also led to altered M. tuberculosis intracellular trafficking and induced a protective proinflammatory response to infection. These findings add a new concept to our understanding of M. tuberculosis-macrophage interactions (i.e., the impact of lung surfactant hydrolases on M. tuberculosis infection).

Perspectives on clinical and preclinical testing of new tuberculosis vaccines

This review hopes to improve the selection of new tuberculosis (TB) vaccines by providing several perspectives on the immunization of humans, mice, guinea pigs, rabbits, and monkeys which have not usually been considered. (i) In human TB vaccine trials, the low rate of healing of Mycobacterium bovis BCG lesions (used as the control group) would distinguish individuals who might be helped by vaccination from the 95% who do not need it and would make these trials more conclusive. (ii) The rabbit immune response to Mycobacterium tuberculosis is much more effective in arresting tuberculosis than those of other laboratory animals, so pulmonary tubercle counting in rabbits should be included in all preclinical TB vaccine testing. (iii) Both delayed-type hypersensitivity (DTH) and cell-mediated immunity (CMI) are necessary to control the growth of M. tuberculosis. The testing of new TB vaccines in mice or in guinea pigs may not detect important antigens needed for human immunization. Mice respond poorly to tuberculin-like antigens that cause DTH. Guinea pigs respond poorly to antigens that cause CMI. Rabbits and humans respond well to both DTH and CMI antigens. Since monkeys are very susceptible to M. tuberculosis, they may not be as useful as rabbits for preclinical vaccine evaluation. (iv) Critical antigens (possibly ESAT-6 or CFP-10) might increase the immunity of the host to a greater extent than that produced by a natural M. tuberculosis infection and therefore would be useful in both prophylaxis and immunotherapy. Such critical antigens would increase the host's ability to neutralize key components of M. tuberculosis that enable it to survive in both laboratory animals and humans.

Graft-extrinsic cells predominate in vein graft arterialization

OBJECTIVE

Vein graft disease involves neointimal smooth muscle cells, the origins of which are unclear. This study sought to characterize and quantitate vein graft infiltration by cells extrinsic to the graft in a mouse model of vein graft disease.

METHODS AND RESULTS

Inferior vena cava-to-carotid artery interposition grafting between C57Bl/6 and congenic beta-galactosidase-expressing ROSA26 mice was performed. Vein grafts were harvested 6 weeks postoperatively and stained with X-gal. More than 60% of neointimal cells derived from the recipient, and 50% of these cells expressed smooth muscle alpha-actin. The distribution of donor and recipient-derived cells within this vein graft wall layer was distinctly focal, consistent with focal infiltration and expansion of progenitor cells. When bone marrow transplantation with congenic green fluorescent protein (GFP)-expressing cells was used in vein graft recipients 1 month before surgery, abundant GFP-expressing cells appeared in the media, but not the neointima, of mature grafts. Endothelial cells in mature grafts derived from graft-intrinsic and graft-extrinsic sources and were, in part, of bone marrow origin.

CONCLUSIONS

Cells extrinsic to the graft, including bone marrow-derived cells, predominate during vein graft remodeling.

Progressive pulmonary tuberculosis is not due to increasing numbers of viable bacilli in rabbits, mice and guinea pigs, but is due to a continuous host response to mycobacterial products

Tuberculosis (TB) kills more people in the world today than any other infectious disease. A better vaccine to prevent clinical tuberculosis is greatly needed. Candidate vaccines are often evaluated by infecting rabbits, mice and guinea pigs by an aerosol of virulent tubercle bacilli and culturing their lungs for viable bacilli at various times thereafter. In all three species, however, the number of viable bacilli usually does not continuously increase until the host succumbs. The number of viable bacilli increases logarithmically for only about 3 weeks. Then, the host develops delayed-type hypersensitivity (DTH) and cell-mediated immunity (CMI), which keep the number of viable bacilli rather constant during the subsequent weeks. In the immunized host, DTH and CMI stop the logarithmic increase sooner than in the unimmunized controls, so that the stationary bacillary levels that follow are lower. This review analyzes host-parasite interactions in the lungs of rabbits, mice and guinea pigs. All three species cannot prevent inhaled fully virulent tubercle bacilli from establishing an infection, but they differ markedly in the type of the disease produced once it is established.

Pulmonary bovine-type tuberculosis in rabbits: bacillary virulence, inhaled dose effects, tuberculin sensitivity, and Mycobacterium vaccae immunotherapy

This report elucidates four aspects of the immunology of pulmonary tuberculosis produced in rabbits: (i) the virulence of bovine-type tubercle bacilli, strain Ravenel S, (ii) systemic factors influencing the generation of visible primary pulmonary tubercles, (iii) differences in tuberculin sensitivity of rabbits and humans, and (iv) the effect of Mycobacterium vaccae immunotherapy on cavitary tuberculosis. Laboratory strain Ravenel S (ATCC 35720) was not fully virulent. Fully virulent strains produce one visible primary pulmonary tubercle for each three bacillary units inhaled. Strain ATCC 35720 produced one such tubercle for each 18 to 107 bacillary units inhaled, indicating that its virulence was reduced by 6- to 36-fold. When a low dose of this Ravenel S strain was inhaled, the host resistance (measured by the number of inhaled bacilli needed to generate one visible primary pulmonary tubercle) was increased at least 3.5-fold compared to the host resistance when a high dose was inhaled. Rabbits and humans differ in the degree and in the maintenance of their dermal sensitivities to tuberculin. Compared to rabbits, humans are 100 times more sensitive to tuberculin. Also, at 33 weeks rabbits with well-controlled cavitary tuberculosis usually showed a decrease in their tuberculin reactions of about 50% from peak values, whereas humans with such well-controlled tuberculosis are thought to maintain strong reactions for many years. These species differences may be due to desensitization to group II mycobacterial antigens in the rabbits because they have a different diet and a different type of digestive tract. M. vaccae immunotherapy of rabbits with cavitary tuberculosis produced no statistically significant effects. Experiments with many more rabbits would be required to prove whether or not such immunotherapy is beneficial.

HYDROLYTIC ENZYMES OF RABBIT MONONUCLEAR EXUDATE CELLS. I. QUANTITATIVE ASSAY AND PROPERTIES OF CERTAIN PROTEASES, NON-SPECIFIC ESTERASES, AND LIPASES OF MONONUCLEAR AND POLYMORPHONUCLEAR CELLS AND ERYTHROCYTES

Oil-induced mononuclear phagocytes (MN) were quantitatively assayed for various hydrolases as unfractionated suspensions of frozen and thawed cells. They apparently contain two proteases. The first, measured with urea- or acid-denatured hemoglobin, was similar to purified Proteinase I of lung with respect to pH optimum (pH 4), stability, hydrolytic and polymerizing activities, and reactions to various inhibitors. The second protease resembled chymotrypsin in its hydrolysis of glycyl-L-phenylalanine amide, acetyl-L-tyrosine ethyl ester and N-benzoyl-DL-phenylalanine-beta-naphthol ester (BPN). With the latter, its pH optimum was between 5.0 and 5.8, and its action was inhibited by diisopropylphosphorofluoridate (DFP) and p-chloromercuribenzoate. When assayed under the above conditions, polymorphonuclear exudate cells (PMN) and red blood corpuscles (RBC) manifested little or no hydrolysis of either hemoglobin or BPN. MN also contained esterases that split methyl butyrate and beta-naphthyl acetate. The pH optimum with the latter was 7.4, and its hydrolysis was partially inhibited by DFP, fluoride, taurocholate, and eserine. PMN had low esterase activity; RBC had little or none. MN, but not PMN or RBC, contained a stable lipase with a pH optimum of 6.1 in maleate buffer. Protamine, NaCl, heat, p-chloromercuribenzoate, ethylenediamine tetraacetate, taurocholate, and DFP were inhibitory, but no appreciable activation occurred in the presence of heparin or serum. Thus it possessed some of the characteristics of Korn's lipoprotein lipase, but not others.

ELECTRON MICROSCOPY OF IN VITRO ENDOCYTOSIS OF T2 PHAGE BY CELLS FROM RABBIT PERITONEAL EXUDATE

Macrophages from rabbit peritoneal exudate cells incubated in vitro with T₂ bacteriophage from 10 up to 120 minutes show phage particles adsorbed to cell membranes, in the process of being engulfed by means of rhopheocytosis, micropinocytosis, and phagocytosis, and localized within dense vacuoles, semi-dense vacuoles, and clear vacuoles of the cytoplasm. The electronmicrographs suggest that newly formed endocytic vacuoles containing phage particles fuse with one another and also fuse with dense bodies of the cytoplasm as they migrate towards the cell interior, thus yielding larger vacuoles of varying densities containing higher concentrations of phage. The polymorphonuclear cells present in a small proportion in the peritoneal exudate cells also endocytosed phage particles. The T₂ particles are found in large cytoplasmic vacuoles surrounded by an electron-opaque material presumably derived from cytoplasmic granules. No disintegration of T₂ phage within the macrophage following incubations up to 120 minutes could be demonstrated; however, disrupted phage particles were noted within cytoplasmic vacuoles of polymorphonuclear leucocytes after 15 minutes' incubation.

THE PARTICULATE HYDROLASES OF MACROPHAGES. I. COMPARATIVE ENZYMOLOGY, ISOLATION, AND PROPERTIES

The contents of selected hydrolytic enzymes of oil-induced peritoneal, normal alveolar, and BCG-induced alveolar macrophages have been studied. On a per cell or nitrogen basis the normal alveolar cells contained considerably more acid phosphatase, cathepsin, acid ribonuclease, lysozyme, and lipase than peritoneal cells. The BCG-induced alveolar macrophage exhibited increased levels of acid phosphatase, lysozyme, and lipase as compared to alveolar macrophages from unstimulated rabbits. The morphological differences between these cells was discussed and electron micrographs of the BCG-induced macrophage presented. Fractionation of the BCG-induced macrophage by differential centrifugation showed that 60 to 80 per cent of the total cell content of acid phosphatase, cathepsin, beta glucuronidase, acid ribonuclease, acid deoxyribonuclease, aryl sulfatase, lysozyme, and lipase were localized in a postnuclear fraction which sedimented at 15,000 g. This fraction also contained the majority of the mitochondria as evidenced by its content of cytochrome oxidase. Non-specific esterase was not localized to this fraction. A separation of the hydrolase-containing particles and mitochondria was achieved by isopycnic sucrose gradient centrifugation. Under the conditions employed, the mitochondria distributed at densities of 1.19 to 1.20, whereas the hydrolase particles sedimented to a density of 1.26 to 1.27. Each of the hydrolases including acid phosphatase, beta glucuronidase, cathepsin, lysozyme, and acid ribonuclease exhibited maximum activities in the same gradient fraction. The isolated granules exhibited enzymatic latency, and activation could be achieved by cycles of freezing and thawing or surface active agents. The majority of each of the hydrolytic enzymes could be liberated in a non-particulate form by mechanical trauma. Macrophages which had been stained supravitally with neutral red were fractionated by differential and gradient centrifugation. More than 70 per cent of the dye could be recovered in the particulate hydrolase fraction. The isolated, stained granules resembled those seen in the intact cell.

Mouse peritoneal macrophages: characterization of functional subsets following Percoll density gradients

Mouse resident peritoneal cells were separated into twelve fractions on Percoll gradients according to their specific density and were thoroughly characterized by Giemsa staining, some biochemical assays, immunophenotyping and phagocytic tests. Among these fractions, the macrophages were mainly represented in 7 subsets of 1.073 to 1.104 g/ml densities. The results of this study emphasize that resident peritoneal macrophages of primo-explantation can be divided into two distinct subpopulations with separate functions, related to the stage of cell maturity. In fact, our results show that one macrophage subpopulation is rich in immature cells, characterized by their peroxidative activity, the expression of F4/80 antigen, Mac-1 and Fc receptors, in correlation with their high specific density; the second subpopulation contains mature macrophages (lower percentage of peroxidase-positive cells) with lower densities and a lower level of expression of the above-mentioned molecules. Antibody-dependent and antibody-independent bacterial phagocytosis, the phagocytic index and Fc gamma RII rosetting increased together with the cell density, and were elevated in the immature cell subpopulation. T and B lymphocytes were also identified in all the macrophage subsets, but in a low proportion.

Pathobiochemical response of tracheobronchial lymph nodes following intratracheal instillation of polyvinylchloride dust in rats

PVC dust, following a single intratracheal instillation (25 mg/rat), was substantially cleared through the lymphatic circulation and progressively accumulated in the tracheobronchial lymph nodes (TBLN) in a time-dependent manner for up to 1 year. The tissue response in TBLN during 60-270 days post-instillation of PVC dust was characterized by progressive increase in total organ fresh weight, dry weight, DNA, RNA and protein contents, concurrent with the proliferation of macrophages and hyperplasia of reticular cells. Active phagocytosis and enhanced hydrolytic activity in TBLN was evident around 270 days post-instillation by the appearance of PVC-laden macrophages near and within the dust foci, and increased activity of acid phosphatase, DNAse, RNAse and beta-glucuronidase. PVC dust caused degeneration of macrophages, and consequent release of hydrolytic enzymes resulted in limited cytotoxicity without inducing reticulination and fibrosis in the TBLN. The histology and clinical biochemistry of liver, kidney, spleen and serum were not altered and there were no detectable PVC particles in these tissues at up to 365 days. It is therefore concluded that lymphatic clearance of intratracheally instilled PVC dust results in its accumulation and mild foreign body reaction in TBLN which is non-fibrogenic at up to 365 days post-instillation.

Mediators, initiating the inflammatory response, released in organ culture by full-thickness human skin explants exposed to the irritant, sulfur mustard

Mediators released from injured human skin that initiate the inflammatory response have not been adequately identified. Organ culture of full-thickness skin explants enables us to do so, because injury to the skin can be made in vitro, eliminating the rapid leakage of serum and infiltration of leukocytes that occur in vivo. In our studies, the military vesicant sulfur mustard (SM) (10 microliters of a 0.01 to 1.0% dilution) was topically applied to injure the epidermis of the explant. Then, the explants were cultured in small Petri dishes, usually for 18 h at 36 degrees C, and the organ-culture fluids were assayed for various inflammatory mediators. We found that the culture fluids from SM-exposed and control explants contained similar amounts of angiotensin-converting enzyme, trypsin-like and chymotrypsin-like proteases, acid phosphatase, beta-glucuronidase, beta-galactosidase, lysozyme, deoxyribonuclease, ribonuclease, interleukin 1, and lactic dehydrogenase. However, the culture fluids from SM-exposed explants contained increased amounts of histamine and plasminogen-activating activity, and often prostaglandin E2, when compared to culture fluids from control explants. After 3 to 4 d in culture, full-thickness human skin explants, when exposed to 0.2% SM (but not when exposed to 1.0% SM), sometimes showed separation of the epidermis and increased collagenase activity (i.e., hydroxyproline release). Thus, histamine (from local mast cells), and prostaglandin E2 and plasminogen-activating activity (probably from both mast cells and epidermal cells) are apparently involved in early mediation of the inflammatory response.

Intracellular tubercle bacilli-alveolar macrophage lysosomal enzymes interaction in experimental tuberculosis

This study is an attempt to understand the mechanism of macrophage activation and its effect on the microbicidal properties of the macrophage. Alveolar macrophages (AM) from normal and BCG-vaccinated guinea pigs were harvested at intervals of 1, 7, 14, 21, and 28 days. Half of the guinea pigs from each group were challenged intratracheally with Mycobacterium tuberculosis H37Rv. In AM, the levels of three lysosomal enzymes, beta-galactosidase (beta-gal), N-acetylglucosaminidase (N-ac), and lysozyme (lyso), were measured histochemically. The percentage of AM staining positively for these enzymes and the intensity of this staining were estimated as parameters of AM activation, along with the number of intracellular bacilli in these cells. Histochemical methods are preferred to biochemical methods as only the former indicate activation in individual cells. The enzymatic responses of AM depend on the type of vaccination and infection. Thus, beta-gal activity was significantly enhanced in immune animals whereas no such enhancement of activity was observed in the case of N-ac and lyso. The N-ac content was higher in infected animals and in the immune group, whereas lyso fluctuated at different time intervals after infection.

Lucigenin chemiluminescence and its relationship to mitochondrial respiration in phagocytic cells

Unstimulated alveolar macrophages, but not polymorphonuclear leukocytes, elicit chemiluminescence from lucigenin which cannot be entirely accounted for by the resting level of superoxide generation. This chemiluminescence was inhibited by both superoxide scavengers and inhibitors of mitochondrial respiration. Although 12-O-tetradecanoyl phorbol-13-acetate addition resulted in a significant increase in cellular superoxide generation, an unexpected decrease in lucigenin chemiluminescence was noted. These results suggest that mitochondria in alveolar macrophages may be a site of lucigenin accumulation and dioxygenation and that 12-O-tetradecanoyl phorbol-13-acetate may modulate this activity.

Macrophage heterogeneity in prostaglandins and thromboxane synthesis: differential activation by Fc- and C3b-dependent bacterial phagocytosis

Resident peritoneal macrophages, obtained from rats, were separated into subpopulations by centrifugation on a Percoll discontinuous density gradient. Nine fractions of pure macrophages were isolated. Each subpopulation was studied for Fc- and C3b-dependent bacterial phagocytosis and assayed for the related synthesis of PGE2, TxA2 and PGI2, measured by their stable metabolites TxB2 and 6-Keto-PGF1. The results show that with decreasing density, which corresponds to a greater maturity, the production of PGE2 increases and that of TxB2 and 6-Keto-PGF1 decreases. The cells of low density were mostly stimulated by IgG-opsonized bacteria, whereas those of high density responded preferentially to C3b- opsonized bacteria. This pattern is roughly similar to the one characterizing the phagocytosis via these two receptors although the correlation is not absolute. It can be concluded that enzymes involved in the metabolism of arachidonic acid, as well as receptors for C3b and IgG, are differentially expressed among resident macrophage subpopulations and thus during macrophage maturation.

Identification of osteoclasts and their differentiation from mononuclear phagocytes by enzyme histochemistry

A double staining method is presented which allows the enzyme histochemical differentiation between osteoclasts (mono- and multinucleated forms) and mononuclear phagocytes (macrophages, multinucleated inflammatory giant cells). Osteoclasts are characterized by a strong acid phosphatase activity whereas macrophages and inflammatory giant cells show a variable non-specific esterase activity. The described method may be useful in studying the osteoclast origin and the extraosseous distribution of these cells.

Superoxide generation by pig alveolar macrophages

Pig alveolar macrophages generate superoxide anions at a rate of 1.8 nanomoles/1 X 10(6) cells/min. The intracellular value of ATP in resting cells was 4.0 +/- 0.1 X 10(-16) mole/cell; in contrast the value in cells generating superoxide anions was 2.0 +/- 0.6. Superoxide generation was increasingly inhibited by exposing cells to adenosine from 0.1 to 1.0 mM. Unlike human macrophages, pig cell production of superoxide anions was not inhibited by exposure to the adenosine analog, 2-Cl-adenosine.

The carbohydrates associated with the surfaces of hamster alveolar macrophages: a study using fluorescein-conjugated lectins

Alveolar macrophages were isolated from the lungs of hamsters by lavage and centrifugation. The harvesting procedure yielded about 5.2 X 10(6) cells per animal and the majority of these cells were viable as assessed by a Trypan blue exclusion test. Monolayers of macrophages were labelled with a series of FITC-conjugated lectins. The results of this study suggest that the surface coating of the alveolar macrophages contains the following carbohydrate groups: N-acetylgalactosamine, N-acetylglucosamine, D-glucose, D-mannose, L-fucose and sialic acid.

The use of 2-thionaphthyl acetate as a substrate for the localization and characterization of nonspecific esterase activity in rat alveolar and peritoneal macrophages

A 2-thionaphthyl acetate substrate was utilized to assess the subcellular distribution of nonspecific esterases in rat pulmonary alveolar and peritoneal macrophages. The enzymatically liberated 2-thionaphthol was visualized at pH 7.1 by utilizing gold as a capture agent. Glutaraldehyde-fixed macrophages derived from healthy animals using standard lavage techniques exhibited a high affinity for the substrate and reaction times were thus relatively short (30-60 min). Alveolar macrophages had heavy reaction product on the external surface of the plasma membrane and membranes limiting cisternae of rough endoplasmic reticulum, Golgi complex and mitochondria. Only a thin layer of reaction density was observed associated with the limiting membranes of lysosomes and phagosomes. Peritoneal macrophages were similarly but much less intensely reactive, although they generally lacked or had very little plasma membrane-associated staining. The 2-thionaphthyl acetate esterase activities in both alveolar and peritoneal macrophages were sensitive to diisopropylfluorophosphate (DFP), while only the latter was inhibited by sodium fluoride. Polyacrylamide gel isoelectric focusing of whole cell homogenates indicated that the 2-thionaphthyl acetate esterase activity was the same as that for alpha-naphthyl acetate in these cells. The data indicate that a significantly different distribution of nonspecific esterase activity results with use of a 2-thionaphthyl acetate substrate in the presence of gold ions than that previously reported with other methods. The rapid penetrability and sensitivity of this substrate make it a potentially useful tool for evaluating subcellular localization of esterase activity and probing characteristics of cellular organelles.

Surface morphology and function of human pulmonary alveolar macrophages from smokers and non-smokers

Pulmonary alveolar macrophages were obtained by saline lavage from 23 healthy male volunteers--10 non-smokers and 13 cigarette smokers. Lavage produced three times as many alveolar macrophages in smokers than in non-smokers. When macrophages from smokers and from non-smokers were incubated in vitro, more cells from smokers adhered to glass, spread out, and showed enhanced nitroblue tetrazolium (NBT) reduction. The surface morphology of alveolar macrophages from smokers showed more with a plate like appearance and ridge like membrane surface, while the macrophages from non-smokers were predominantly spherical with ruffles. The proportions of cells which stained highly for beta galactosidase were 55% in smokers and 11% in non-smokers. Thus, in a resting state in vitro, alveolar macrophages from smokers were more active than those from non-smokers. When, however, macrophages from smokers and non-smokers were incubated with immunobeads and with opsonised or non-opsonised BCG, the phagocytic activity and stimulated NBT reduction of alveolar macrophages from smokers were similar to or somewhat less than those of non-smokers.

Metabolic characteristics of cells cultured from human umbilical blood vessels: comparison with 3T3 fibroblasts

Little metabolic information is available for cells cultured from umbilical vascular tissue. These studies were undertaken to compare the metabolism of cells isolated from human umbilical arteries and veins with that of umbilical vascular segments. These studies also compared umbilical vascular cells to standard fibroblast preparations. Oxygen consumption by umbilical venous cells or tissues was greater than that for either arterial cells or tissues. Cellular adenosine triphosphate (ATP) content was greater in umbilical venous than arterial cells. However, an oxidation-phosphorylation ratio (R) was constant for either arterial or venous cells. Oxygen consumption by vascular cells was greater than that by nonvascular cells, as was cellular ATP content. R for nonvascular cells was much greater than that for vascular cells, indicating loose coupling between oxygen consumption and cellular ATP content. Finally, cellular oxygen consumption was dependent upon cell density, and upon media serum content in vascular endothelial cells. We conclude therefore that the metabolism of umbilical vascular cells in culture reflects that of the parent tissue but is different from that of either vascular or nonvascular fibroblasts.

Improvement in the histochemical demonstration of acid phosphatase, beta-galactosidase and nonspecific esterase in glycol methacrylate tissue sections by cold temperature embedding

A simple, cold-embedding method (on cracked ice at 2 C) is presented for the demonstration of acid phosphatase, beta-galactosidase and nonspecific esterase in glycol methacrylate tissue sections.

Tissue localization of complement component 3 receptor-bearing cells in lymphoid tissue after injection with complete Freund adjuvant

Localizations of complement component 3 (C3) receptor (C3R)-bearing cells in lymph nodes obtained from normal guinea pigs or from guinea pigs inoculated with complete Freund adjuvant were examined by staining with fluorescein-labeled anti-guinea pig C3 antibody after treatment with aggregated rabbit immunoglobulin M bound with guinea pig complement. In normal lymph nodes, a small number of C3R-positive cells were observed in the cortical and medullary areas. Non-granulomatous lymph nodes from complete Freund adjuvant-inoculated animals showed a number of C3R-positive lymphocytes in a mantle zone of the secondary follicles between the follicles and medullary cords, whereas in the paracortical areas and germinal centers, only a few positive cells were scattered. Long-lasting existence of positive cells was seen in the epithelioid cell granuloma, although the staining patterns were different from those of the lymphocytes. The appearance of a number of C3R-bearing lymphocytes in lymph nodes from complete Freund adjuvant-inoculated animals might be an expression of adjuvant activity.

Permissiveness of rabbit monocytes and macrophages for herpes simplex virus type 1

The permissiveness of rabbit monocytes and macrophages for herpes simplex virus was examined. Peripheral blood monocytes, alveolar macrophages, and peritoneal exudate macrophages were studied for their ability to replicate herpes simplex virus strains RE and KOS. Results indicated different degrees of interaction with virus depending on the macrophage type. Only peritoneal exudate macrophages showed evidence of virus replication. Productive infection was limited, with only a small number of cells (0.02%) yielding infectious virus. Higher numbers of cells appeared to be abortively infected. Approximately 40% expressed antigens, whereas virtually all were killed by exposure to virus. Coreless particles were seen by electron microscopy in about one-third. Alveolar macrophages were also killed by virus and showed evidence of virus adsorption, but showed no indication of productive or abortive infection. Monocytes neither adsorbed nor replicated virus, and viability was unaffected. Results suggest that differences in degrees of cellular maturation or differentiation, or both, account for the spectrum of interactions seen between herpes simplex virus and rabbit macrophages.

Histochemical studies of lysosomal enzyme and nitroblue tetrazolium reduction of phagocytes in the cerebrospinal fluid of patients with infectious diseases of the central nervous system

Lysosomal enzyme levels and nitroblue tetrazolium (NBT) reduction of phagocytes in the cerebrospinal fluid (CSF) of patients with infectious diseases of the central nervous system (CNS) were studied histochemically to evaluate the function of phagocytes. Lysosomal enzymes of acid phosphatase and beta-galactosidase were demonstrated in mononuclear phagocytes and leptomeningeal cells, but not in polymorphonuclear leukocytes (PMN) and lymphocytes. In tuberculous meningitis, more than 60% of the cells were positive for the enzymes as compared with less than 30% for other diseases. Besides, the cells which stained highly for the enzymes were often found in the CSF of tuberculous meningitis. The lysosomal enzyme levels in the cells were dependent on the nature of the infection rather than on the intensity of inflammation when judged by total cell count in the CSF. On the other hand, reduced NBT formazan was found in PMN, mononuclear phagocytes, and leptomeningeal cells. The intensity of NBT reduction by these cells correlated well with the total cell count in CSF; i.e., enhanced NBT reduction by phagocytes reflected the intensity of the inflammation in the subarachnoid space. Thus, histochemical study of phagocytes in CSF can provide useful additional aids to the diagnosis of the nature and stage of CNS infection.

Macrophage functional heterogeneity in vivo. Macrolocal and microlocal macrophage activation, identified by double-staining tissue sections of BCG granulomas for pairs of enzymes

BCG lesions were produced in the skin of rabbits, and biopsies were performed at 7, 21, and 42 days, when they were developing, maximal in size, and almost healed, respectively. Tissue sections were prepared and stained histochemically for several enzymes. The percentage of cells stained for a given enzyme and the distribution of such cells within lesions of various ages were determined. Seven-day BCG lesions contained few esterase- and beta-galactosidase-positive macrophages, but 21-day lesions contained many, especially in the viable and nonviable tuberculous granulation tissue at the edge of the now prominent caseous necrotic center. Both 7-day and 21-day lesions contained many acid phosphatase- and cathepsin-D-positive macrophages, which were numerous in the more peripheral parts of the lesion, where little or no necrosis was present. Enzyme patterns in 42-day lesions resembled those in 21-day lesions. The role of each of these enzymes in the development and regression of the BCG lesion is unknown. Nonetheless, these studies clearly demonstrate that this macrophage population is heterogeneous and that macrophages carry out different functions in different parts of the lesion at different times. Histochemical techniques were developed to stain two enzymes in the same tissue section. The first stain usually contained a naphthol substrate and produced a red color; the second stain contained an indoxyl substrate and produced a blue color. A cell staining with both was colored purple. The peroxidase-antiperoxidase immunocytochemical technique for cathepsin D (producing a red color) was also employed. 1) Red esterase (hydrolyzing naphthol AS-D acetate) and beta-galactosidase, and 2) red esterase and blue esterase (hydrolyzing 5-bromo-4-chloro-indoxyl acetate), probably the same enzyme, were usually present in the same macrophage. In contrast, each of the following enzyme pairs was usually present in a different macrophage: 3) cathepsin D and beta-galactosidase, 4) cathepsin D and blue esterase, 5) acid phosphatase and beta-galactosidase, and 6) acid phosphatase and blue esterase. Roughly 10% of the macrophages stained for one enzyme existed side by side with macrophages stained for a different enzyme. These results suggest that local macrophage activation is under two levels of control. The first, macrolocal control, would determine the overall enzyme distribution in the lesion; whereas the second, microlocal control, would determine enzyme distribution on a cell-by-cell basis, ie, how two neighboring macrophages can each be rich in a different enzyme.

Chronologic changes of activities of naphthol AS-D acetate esterase and other nonspecific esterases in the mononuclear phagocytes of tuberculous lesions

Nonspecific esterases of mononuclear phagocytes (MNs) were studied histochemically in the developing and healing tuberculous lesions produced in rabbit skin by bacille Calmette Guérin (BCG). Nonspecific esterases were assayed with the following substrates: naphthol AS-D acetate (AS-D), naphthol AS-D chloroacetate (AS-D Chl), naphthol AS acetate (AS) and alpha-naphthyl acetate (alpha-N), beta-Galactosidase, a lysosomal enzyme of MNs, was also assayed as a marker of MN activation. The number of MNs hydrolyzing AS-D Chl, AS, and alpha-N increased for 2 to 4 weeks after infection. These chronologic changes were similar to that of beta-galactosidase. In contrast, MNs hydrolyzing AS-D appeared predominantly in the healing lesions five to six weeks after infection. These MNs had the morphologic features of balloon-like cells. They contained few lysosomes and gathered in clumps far from the caseous center. The activity of the AS-D esterase was almost completely inhibited by various trypsin inhibitors, but not by the serine esterase inhibitor of phenylmethylsulfonyl-fluoride. These results suggest that the AS-D esterase is a trypsin-like esterase which participates in the healing of tuberculous lesions.

Prostaglandin biosynthesis in pulmonary macrophages

Cultured rabbit alveolar macrophages, prelabeled with 14C-arachidonic acid (AA), released into the medium a trace amount of labeled prostaglandins (PG) as well as their precursor, AA. Phagocytosis of zymosan, heat-killed Staphylococcus, or bacille Calmette-Guérin (BCG) increased the AA and PG release to 2--2.5 times control values. The released PGs consisted of PGE2, D2, F2 alpha, and 6-keto F1 alpha. Phagocytosis of latex particles had no effect on PG release. Indomethacin inhibited release of PGs but did not affect AA release at low doses. Analysis of the cellular lipids showed that zymosan decreased the radioactive label in phosphatidylcholine (PC), but not in other phospholipids or neutral lipids, suggesting that PC is the main source of AA for PG synthesis in pulmonary macrophages. Cytochalasin B (CB) at phagocytosis-inhibiting doses or below, markedly increased PG synthesis by zymosan-treated macrophages. These data suggest that PG release is not dependent on engulfment of the particles. Phagocytosis of zymosan (but not latex) also resulted in the release of two lysosomal enzymes, acid phosphatase and beta-glucuronidase, which appeared temporally associated with the release of PGs (but not to phagocytosis). Furthermore, CB augmented the zymosan-stimulated release of these enzymes at the same doses stimulating PG synthesis. However, indomethacin, at a dose completely inhibiting PG synthesis, failed to block lysosomal enzyme release. Thus, the coincidental release of PGs and lysosomal enzymes is not the result of a regulatory role of PGs in the release of lysosomal enzymes, but probably is the result of a common pathway of stimulation. (Am J Pathol 97:137--148, 1979).

The origin of microglial cells

The rat brain has been studied between 6 hours after birth and 100 days, using histochemical techniques for acid phosphatase and peroxidase, and silver impregnation for microglial cells. The results indicate that microglia come initially from acid phosphatase-positive cells of the meninges. These invade the nervous parenchyma and transform into ramified microglia. At 3 days of age similar cells are present on the outer surface of the large blood vessels, from which site they migrate into the nervous parenchyma. In 100 days old rats the acid phosphatase-positive cells are practically all pericytes. None of the microglial cells or their precursors give a positive reaction for peroxidase.

Histochemical demonstration of enzyme activities in plastic and paraffin embedded tissue sections

Histochemical staining for enzymes is usually performed on frozen sections. This report lists the longer incubation times required to demonstrate esterase, acid phosphatase, beta-galactosidase, and cytochrome oxidase in plastic embedded and ruotine paraffin embedded tissues. The sections embedded in plastic, i.e. water soluble methacrylate (Polyscience's JB-4) and cut at 2 micrometers, were far superior to frozen sections and paraffin embedded sections both in tissue detail and in the localization of the histochemical reaction product.

Quantitative stereological studies on the mechanism of immunosuppressive effect of nitrogen mustards of benzimidazole derivatives: the role of polymorphonuclear leukocytes and mononuclear phagocytes

The effect on antigen uptake and digestion in macrophages and polymorphonuclear leukocytes (PMNL) of 2 compounds of a series of benzimidazole nitrogen mustard derivatives has been investigated by ultrastructural quantitative stereological techniques in order to enlighten some mechanisms of the immunosuppressive effect of especially one of the chemicals. One compound, ZIMET 3393 (Cytostasan), is a powerful cancerostatic with only moderate immunosuppressive side effects while ZIMET 3164 proved an effective immunosuppressant with low cytostatic action. Results of a recent study (FRITSCH and GOTHE 1979) have lent support to the hypothesis that immunosuppression can be induced by an inhibition of antigen processing by macrophages through a membrane-stabilizing effect of the chemicals under investigation. It can be shown in the present study that in the case of ZIMET 3164 an increased competitive antigen phagocytosis and digestion takes place in PMNL. This alternative pathway of antigen processing is suggested to be ineffective with respect to enhancement of immune responses compared with that through macrophages, thus providing an additional possible mechanism of chemical immunosuppression.

The location of non-specific esterase in human lung macrophages. An ultrastructural study

The non-specific carboxyl (serine) esterase of the human pulmonary alveolar macrophage was localized ultrastructurally using alpha-naphthyl acetate and hexazotized pararosanilin. The reaction product principally outlined the outer side of the plasma membrane. Consequently, this esterase is an ectoenzyme which may function as mediator of cell response to injurious agents from the outside.

Extracellular hydrolytic enzymes of rabbit dermal tuberculous lesions and tuberculin reactions collected in skin chambers

To evaluate extracellular hydrolytic enzymes in an in vivo system, plastic chambers were glued over rabbit dermal BCG lesions in various stages of development, after the central epithelium was removed with a scalpel. They were filled with tissue culture medium and left in place 2 days. The following enzymes in the fluid were assayed: collagenase (an enzyme secreted but not stored in macrophages); lysozyme (both secreted and stored); DNase and RNase (released on cell death and possibly regurgitated but not secreted); and, as a control, lactic dehydrogenase (released only on cell death). Tissue sections were prepared and studied histologically for the type of cell infiltrate, for beta-galactosidase (our marker enzyme for macrophage activation), and for necrosis. At 11 and 18 days of age the BCG lesions were largest and the number of activated macrophages in the chamber beds was highest. At this time the levels of the five enzymes assayed in the chamber fluids reached their peaks, tuberculin hypersensitivity was well developed, and the bacilli components would still be plentiful. In general, the chamber fluids from 11- and 18-day BCG lesions contained higher enzyme levels than chamber fluids from tuberculin reactions. Active collagenase was only detected in fluids from such BCG lesions. Evidently, the serum in the chamber fluids was sufficient to inhibit the lower amounts of collagenase probably released from smaller BCG lesions and tuberculin reactions (and from the 2-week polystyrene lesions that were also evaluated). These studies demonstrate that in chronic inflammatory reactions, both acid-acting and neutral-acting hydrolytic enzymes are released extracellularly. Tissue components would be hydrolyzed locally wherever the acid-acting hydrolytic enzymes encounter a drop in pH and wherever the concentration of neutral-acting hydrolytic enzymes exceeds the concentration of their inhibitors.

Light and electron microscopic demonstration of some lysosomal enzymes in the amoeboid microglia in neonatal rat brain

A cytochemical study of the amoeboid microglial cells in the brain of the neonatal rat has shown that these vacuolated cells exhibit strong acid phosphatase, aryl sulphatase and adenosine triphosphatase (ATPase) activities. Endogenous peroxidase, however, was not present. With the electron microscope the reaction product of acid phosphatase was found to be localized in some of the Golgi cisternae, in the majority of the electron-dense secretory granules, and in an occasional long tubular profile. The secretory granules were not uniformly stained for this enzyme, some showing only a focal reaction or none at all. The distribution of the activity of aryl sulphatase corresponded to that of acid phosphatase except that all the granules appeared to contain the former enzyme. With the light microscope the amoeboid microglial cells were intensely stained for ATPase. From these observations it was concluded that amoeboid microglia are active phagocytes and their enzyme-rich secretory granules are lysosomes.

Enzymatic basis for bioenergetic differences of alveolar versus peritoneal macrophages and enzyme regulation by molecular O2

Alveolar macrophages (AM) and peritoneal macrophages (PM) originate from common precursor cells, but function in different O2 environments. In the present studies, the impact of different O2 tensions on cell metabolism has been quantitatively determined, an enzymatic basis for these differences established, and a mechanism which regulates enzymatic differences demonstrated. O2 consumption and lactate production were compared in rabbit AM and PM in air and nitrogen. In air, AM demonstrate significantly greater O2 utilization. In nitrogen, (where glycolysis is the major source of energy provision) lactate production is two- to threefold greater in the PM. A comparison of several enzymes of energy metabolism in AM and PM indicate that one basis for the differences in cell energetics is a difference in activity of key enzymes of both the oxidative phosphorlyative and the glycolytic sequences. Exposure of cultivated AM to hypoxic conditions results in changes in the activity of these enzymes such that the AM closely resembles the PM. A key enzyme in oxidative phosphorylation (cytochrome oxidase) shows decreased activity and reaches values similar to those found in the PM. A key enzyme in glycolysis (pyruvate kinase) shows increased activity to values resembling those found in the PM. These alterations in enzyme pattern occur in isolated cell systems, suggesting that molecular O2 modifies the intrinsic cellular regulation of some enzymes of energy metabolism. Alterations in O2 tension may lead to alterations of the rate of biosynthesis and (or) the rate of biodegradation of key enzymes involved in oxidative phosphorylation and glycolysis. In turn, the alteration of enzyme patterns leads to a more suitable bioenergetic pattern as a function of O2 availability.

Further studies on the intracellular behavior of Torulopsis glabrata

The growth of Torulopsis glabrata was inhibited in glucose-peptone broth containing 10 to 20% normal human serum. Addition of iron to the medium diminshed the fungistatic effect. The intracellular growth of T. glabrata was remarkably restricted within mouse macrophages maintained in vitro, but this growth restriction was not caused by the limitation of iron imposed by the serum in the medium. The intracellular growth of T. glabrata within a very small percentage of the macrophages was not obviously related to the failure of lysosomal fusion to the phagosomes in those cells. The studies did not permit definite conclusions regarding the viability of the inhibited yeasts, but results suggested that a large portion of them survived. Potentially misleading artifacts of the technique for assessment of the intracellular behavior of the fungus were detected and are discussed.

Host-parasite interactions with peritoneal macrophages of mice and rats in vitro and in vivo

This paper deals with the intracellular multiplication of mycobacteria in peritoneal macrophages from mice and rats immunized with tubercle bacilli or pretreated with Triton WR 1339. If unstimulated macrophages were used, almost unrestricted multiplication of mycobacteria was observed in macrophages from both vaccinated and pretreated hosts after infection of the cells in vitro. Only when the infection of the cells was perfored in the peritoneal cavity of vaccinated hosts did the macrophages display a high degree of inhibition. This striking difference in the behavior of macrophages infected in vitro and in vivo is explained by the local inflammation caused by the intraperitoneal infection, which leads to an influx of T-cell mediators. When macrophages from hosts pretreated with Triton WR 1339 were used, inhibition of the multiplication of mycobacteria within cells infected in vitro or in vivo was very slight, though this compound displayed a marked protective effect in the host. Addition of streptomycin to the culture medium caused a strong inhibition of intracellular mycobacteria even in small concentrations; there was no difference between normal and "immune" macrophages. When rats were infected with virulent tubercle bacilli, they were initially fully susceptible to the infection but showed rapid onset of a strong immune response.

Macrophage esterase: identification, purification and properties of a chymotrypsin-like esterase from lung that hydrolyses and transfers nonpolar amino acid esters

A chymotrypsin-like esterase was purified from beef lung. This lysosomal enzyme, not previously characterized, seemed to be composed of two or more forms with molecular weights of about 52 000. It hydrolysed N-benzoyl-DL-phenylalanine beta-naphthol ester at acid and neutral pH; it polymerized L-phenylalanine methyl ester(Phe-OMe) at neutral pH; and it transferred the Phe-residue from Phe-OMe to hydroxylamine at neutral pH. Phenylmethanesulfonyl fluoride, an inhibitor of hydrolytic enzymes with serine in their catalytic site, inhibited this enzyme, but pepstatin, the cathepsin D (EC 3.4.4.23) inhibitor, did not. Sulfhydryl reagents were not required for activity. Macrophages, especially pulmonary alveolar macrophages, were a rich source of this esterase, so it is likely that the enzyme purified from lung came from its macrophages. The esterase hydrolysed and transferred monoamino acid esters, especially those of the aromatic type. Cathepsin C, the dipeptidyl peptide hydrolase (EC 3.4.14.1), acted only on dipeptide esters and amides. Pancreatic chymotrypsin acted on both monoamino acid and dipeptide esters. The chymotrypsin-like esterase did not hydrolyse hemoglobin, casein, or plasma albumin. Thus its proteolytic activity, if present, must be limited to specific substrates, as yet unknown.