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PubMed2003

Association of Flavobacterium psychrophilum with rainbow trout (Oncorhynchus mykiss) kidney phagocytes in vitro.

The capacity of virulent and non-virulent strains of Flavobacterium psychrophilum of different serotypes to associate with isolated rainbow trout (Oncorhynchus mykiss, 300-500 g) kidney phagocytes was evaluated in vitro. The results showed that F. psychrophilum was associated with the phagocytes but large differences in association were observed between the different bacterial strains examined. These differences in association with the phagocytes was not clearly related to the serotype or virulence of the bacteria, although all strains tested of the non-virulent serotype FpT showed strong association with the isolated phagocytes. A competitive association assay with treatment of the phagocytes with seven different carbohydrates, suggested a role for N-acetylneuraminic acid (sialic acid) in the binding of F. psychrophilum to phagocytes. A significant dose dependent inhibition of the association was observed with sialic acid. Treatment of F. psychrophilum with sodium-metaperiodate showed that carbohydrate components play a role in the adhesion of the bacteria to the phagocytes. The results indicate that the binding of F. psychrophilum to rainbow trout kidney phagocytes can be mediated by opsonin independent cell-receptor adhesion. All tested strains seemed to be non-cytotoxic for rainbow trout kidney phagocytes in vitro suggesting that a phagocyte toxin is not necessary for the virulence of F. psychrophilum

Animals↗
PubMed1975

Identification and characterization of the monoblast in mononuclear phagocyte colonies grown in vitro.

A liquid culture technique for growing mononuclear phagocyte colonies on a glass surface is described. This useful and reliable technique made it possible to study immature mononuclear phagocytes. In the mononuclear phagocyte colonies the cells grow separate from each other in a single layer. Three types of cells are recognized in these colonies, namely nondividing macrophages, and proliferating promonocytes and monoblasts. The macrophage and the promonocyte exhibit the typical characteristics previously demonstrated by the other methods, whereas the monoblast could only be fully characterized by the present liquid culture method. This proliferating cell (labeling index with [3H]thymidine, 92-96%) is almost round (diameters, 10 X 10 mum), has only a small rim of strongly basophilic cytoplasm, almost devoid of granules, and shows a certain degree of ruffling of the cell surface. The monoblast is positive for esterase with alpha-naphthyl butyrate as substrate (91%), for peroxidase (78% in the peroxidase-positive colonies), and lysozyme (43%). The monoblast is able to pinocytize dextran sulphate (15-20%) and to phagocytize opsonized bacteria (20-30%), latex particles (47%), and IgG-coated red cells (96%). IgG receptors (94%) and complement receptors (16%) are present at the cell surface. In these respects the monoblast has the typical characteristics of the mononuclear phagocytes, but its properties show it to be a more immature cell type than the promonocyte. On the basis of these criteria and the sequence of appearance of the different cell types during incubation and during the development of the individual mononuclear phagocyte colony, monoblasts being present before promonocytes appear in the colony, it is concluded that the monoblast is the precursor of the promonocyte. In these cultures granulocyte colonies are also formed, consisting of myeloblasts, (pro)myelocytes, stabs, and polymorphonuclear neutrophils. Besides the typically tight structure of this kind of colony, the granulocytic cells themselves are quite distinct from the mononuclear phagocytes by their morphology, cytochemical characteristics (e.g. all negative for esterase with alpha-naphthyl butyrate, but 96% positive with N-acetyl DL-alanyl 1-naphthylester), functional characteristics (pinocytic index 13-21%; phagocytic index; for opsonized bacteria 15-36%, for latex particles 10%, and for IgG-coated red cells 0%), and their very small number of IgG receptors and lack of complement receptors. On the basis of these criteria, these granulocytic cells are easily distinguished from the immature cells of the mononuclear phagocyte colonies. The present study confirms the conclusion that the mononuclear phagocytes are a separate cell line, quite distinct from the granulocytic series, since even the most immature cells so far identified--the monoblast and the myeloblast--have quite different characteristics.

Acid Phosphatase↗
PubMedDate not supplied

Application of a fluorochrome-lysostaphin assay to the detection of phagocytic and bactericidal disturbances in human neutrophils and monocytes.

The evaluation of phagocytic and microbicidal activities of the blood neutrophils has been recognized as one of the important tools for investigating phagocytic dysfunctions in patients with recurrent infections. In the present study, these activities were examined in neutrophils and monocytes from healthy adults and patients affected by primary phagocytic dysfunctions by using a modified fluorochromic microbicidal assay, discriminating simultaneously the extracellular adherence, ingestion and intracellular killing of Staphylococcus aureus Cowan I. The assay employs acridine orange staining, as described in Bellinati-Pires et al. (1989) (AO assay), but was modified by the addition of an alternative leukocyte treatment with 0.5 U/ml of lysostaphin (LS) for 5 min at 37 degrees C, after phagocytosis (AO-LS assay). The LS treatment was standardized to eliminate staphylococci adhered to the outer surface of the phagocytes without affecting the determination of intracellular live or dead bacteria, as demonstrated in normal neutrophils and monocytes. Our purpose in this study was to compare AO and AO-LS assays in order to evaluate the effect of LS on the determination of actually ingested staphylococci and to provide a means for improving the fluorochromic assay for detecting phagocytic defects, as well as bactericidal disturbances. By using the AO-LS assay, decreased ingestion of staphylococci by neutrophils in Chediak-Higashi Syndrome (CHS) was demonstrated. However, increased staphylococci adherence, as well as ingestion, was observed in neutrophils or monocytes from chronic granulomatous disease (CGD) patients, comparing AO and AO-LS assays. Bactericidal defect, which is a common feature in CHS and CGD, was detected in neutrophils or monocytes in both assays. We emphasize that such alterations were deduced by comparing the patients' results with those obtained from their respective normal controls and with the normal range of values previously established for 160 healthy adults. No alteration was observed in hyper IgE syndrome phagocytes. Despite the possible penetration of LS into the leukocytes, as stated in other studies, we concluded that a short period of phagocyte incubation with this enzyme increased the sensitivity of the fluorochromic assay to detect phagocytic defect without affecting the determination of the bactericidal activity. Moreover, comparations between AO and AO-LS assays may be important in the study of the initial pathways of staphylococci phagocyte interaction, including adherence by non-phagocytic receptors.

Adult↗
PubMed2001

Evaluation of phagocytic activity in human monocyte-derived dendritic cells.

Dendritic cells play a central role in initiation of primary T lymphocyte responses to foreign antigens. Their potency in antigen presentation vis-à-vis reported low or lack of ability to phagocytize particulate matter has limited our understanding of the role that they play in inducing immunity to particulate antigens. One hypothesis is that dendritic cells may possess a high phagocytic capacity when immature and located in peripheral tissues, which they lose on maturation. Our goal was to characterize the phagocytic capacity in human immature dendritic cells. The phagocytic capacity of human monocyte-derived immature dendritic cells was studied by morphological and morphometric means, and compared to that of professional phagocytes, human alveolar macrophages, their progenitors, the peripheral blood monocytes, and mature dendritic cells. Phagocytic index (proportion of phagocytic cells) was decreased by 42.8% (immature dendritic cells) and 74.2% (mature dendritic cells) with respect to monocytes. Similarly, the phagocytic index was decreased by 46.5% (immature dendritic cells) and 75.9% (mature dendritic cells) with respect to macrophages. Volume density of phagocytized particles was decreased by 76.1% (immature dendritic cells) and 96.7% (mature dendritic cells) with respect to the monocytes. However, volume density was decreased by 34.3% (immature dendritic cells) and 91% (mature dendritic cells) with respect to alveolar macrophages. These results show that human monocyte-derived immature dendritic cells possess a phagocytic capacity that is lower than that of peripheral blood monocytes and alveolar macrophages but higher than that of mature dendritic cells.

Cells, Cultured↗
PubMed1981

Effect of calcium on superoxide production by phagocytic vesicles from rabbit alveolar macrophages.

Phagocytic vesicles from rabbit lung macrophages produced superoxide in the presence of NADH or NADPH. At 37 degrees C, these vesicles generated 51+/-7.8 nmol O(2) (-)/min per mg protein in the presence of 0.5 mM NADPH. The apparent K(m) for NADPH and NADH (66 and 266 muM, respectively), the pH optimum for the reaction (6.9), and the cyanide insensitivity were similar to properties of plasma membrane-rich fractions of stimulated polymorphonuclear leukocytes studied by others. The activity of the phagocytic vesicles was trypsin sensitive. The specific superoxide-generating activity of macrophage phagocytic vesicles isolated from cells incubated up to 90 min with phagocytic particles remained constant. Calcium in micromolar concentrations inhibited the NADPH-dependent O(2) (-)-generating activity of phagocytic vesicles. In a physiological ionic medium (100 mM KCl, 2.5 mM MgCl(2), 30 mM imidazole-HCl, pH 6.9), a maximal inhibition of O(2) (-) generation by phagocytic vesicles of 80% was observed at 40 muM free Ca(2+). The half maximum inhibitory effect was at 0.7 muM Ca(2+). Variations of the calcium concentration resulted in rapid and reversible alterations in O(2) (-)-forming activity. Preincubation of phagocytic vesicles in the presence of EGTA rendered their O(2) (-) generation rate in the presence of NADPH insensitive to alterations in the free calcium concentration. This desensitization by low EGTA concentrations (</=100 muM) was reversible by the addition of excess calcium, but desensitization by high EGTA concentrations (>1 mM) was not reversible by the addition of calcium either in the presence or absence of purified rabbit lung macrophage or bovine brain calmodulins. Furthermore, trifluoperazine, a drug that inhibits calmodulin-stimulated reactions, did not alter the activity or the calcium sensitivity of the superoxide-generating system of sensitive phagocytic vesicles. Peripheral plasma membrane vesicles (podosomes) prepared by gentle sonication of macrophages possessed on O(2) (-)-generating system with similar properties to those of phagocytic vesicles. We conclude that the activated O(2) (-)-generating system of rabbit lung macrophages has its initial localization in the plasmalemma and undergoes subsequent internalization into phagocytic vesicles, where it can function for prolonged periods of time. Calcium at concentrations likely to exist in macrophage cytoplasm exerts a regulatory effect on the activated system.

Animals↗
PubMed1987

Phagocytic capacity of normal and malignant rat glial cells in culture.

The phagocytic capacity of 4 continuous rat glioma cell lines (BT2C, BT4Cn, BT5c, and 9L) and normal BD IX fetal rat glial cells in culture has been studied. This was done by flow cytometric measurements of single cells from monolayer cultures having ingested fluorescent bacteria, zymosan particles, red blood cells, or fragments of normal glial cells. In addition, phagocytosis was studied in a three-dimensional culture system. The BT4Cn, BT5C, and 9L cell lines were tumorigenic and invasive both in vivo and in organ culture in vitro. In contrast, BT2C has shown variable tumorigenicity and does not seem to be invasive. The phagocytic capacity of the cell lines was compared to their destructive properties during invasion. Depending on the particle type, 30-40% of the normal glial cells were phagocytic. The fractions of phagocytic glioma cells were dependent on the particle type and the prey load. Of the invasive cell lines, BT5C showed high phagocytic activity both in monolayer and three-dimensional cultures. Two of the invasive cell lines (BT5C and 9L) had about the same fraction of phagocytic cells as normal glial cells. These 2 cell lines showed highly destructive growth during invasion. In contrast, the third invasive cell line (BT4Cn) had almost no phagocytic cells. The BT4Cn cells showed single-cell invasion with little destruction of target tissue. The noninvasive cell line (BT2C) showed low phagocytic activity, and almost no destruction was observed in the border zone between tumor cells and normal tissue. Phagocytosis seems to be an inherent property of both normal and malignant glial cells, although the fraction of phagocytic cells varies from one cell line to another. In organ culture high phagocytic capacity of invasive glioma cells seems to be related to destructive activity on the normal brain tissue during invasion.

Animals↗
PubMed1983

Autoradiographic and cytochemical studies of phagocytic cells in selected fibre tracts of the mouse periodontium.

Proliferative and protein synthetic activities of phagocytic cells of specific fibre tracts of the periodontium of C57Bl mice were employing autoradiographic techniques; these were combined with a histochemical technique for horseradish peroxidase (HRP) as a marker for phagocytic activity. Animals were injected either with [3H]thymidine as a marker for proliferative activity, or with [3H]proline as a marker for protein synthetic activity prior to HRP injection. Blocks from the maxillae of experimental and control animals were fixed, decalcified, and sectioned at 50 micrometers. These were incubated with HRP localization media, dehydrated and flat embedded in Epon 812 wafers. The entire length of the periodontium, including adjacent tooth and bone, were selectively cut from the wafers, mounted on epoxy blocks and serially sectioned at 2 micrometers. Slides containing these sections were then dipped in NTB-3 nuclear track emulsion, and after appropriate exposure times, were developed and post-stained. Sections were examined microscopically, employing an ocular grid, and phagocytic cells within each area examined were delineated as either 'fibroblast-like' (FL cells) or 'endothelial/macrophage-like' (EML cells) according to criteria such as morphology, location, orientation and proximity to a vascular channel. They were then subclassified as labelled or unlabelled with respect to the autoradiographic markers. The thymidine labelling index obtained for non-phagocytic FL cells was 3.09%; this was more than twice that for phagocytic FL cells (1.35%). Similarly phagocytic FL cells in all regions studied incorporated less than half as much [3H]proline as did their non-phagocytic counterparts. This was determined by silver grain counts over HRP-stained and unstained cells using a matched pair system. In addition, the variation of the relative number of phagocytic FL cells in specific fibre tracts suggested a relationship to functional demand. The distribution of these cells was closely related to experimentally determined rates of protein turnover. Phagocytic FL cells have a markedly reduced proliferative rate and synthesize proline-containing proteins at a reduced rate. This may reflect protein production primarily for the purpose of cell maintenance. These findings are consistent with the presence of subpopulations of fibroblasts (or fibrocytes) developmentally or functionally modified for phagocytosis; alternatively, this could signify modulation of fibroblasts from primarily biosynthetic activities to degradative functions in response to varying microenvironmental conditions.

Animals↗
PubMed1979

The intracellular survival and growth of gonococci in human phagocytes.

In reassessment of previous tests for intracellular survival, results have been confirmed and additional evidence obtained indicating that some gonococci can survive and multiply in human phagocytes. Use was made of the ability of penicillin to penetrate phagocytes and to kill only actively growing organisms. In microscopic counts on 33 urethral exudate smears, an average of 49% of gonococci were associated with polymorphonuclear phagocytes. The organisms were unevenly distributed amongst the phagocytes, with most cells uninfected and some containing large numbers. Many phagocytes also remained uninfected in tests in vitro with low gonococcal inocula although experiments with large inocula showed that most phagocytes could ingest gonococci. It is proposed that ingestion of one gonococcus may stimulate the phagocytes to take up more. Phagocytes were killed and disintegrated after ingesting large numbers of gonococci and similar effect in vivo may be responsible for the large clumps of organisms seen in urethral exudate. These results underline the probable importance in the pathogenesis of gonorrhoea of intracellular survival in phagocytes.

Blood Bactericidal Activity↗
PubMed2001

Opsonized virulent Edwardsiella tarda strains are able to adhere to and survive and replicate within fish phagocytes but fail to stimulate reactive oxygen intermediates.

Edwardsiella tarda is responsible for hemorrhagic septicemia (edwardsiellosis) in fish and also causes diseases in higher vertebrates such as birds, reptiles, and mammals, including humans. Interactions of E. tarda with blue gourami phagocytes were studied by light microscopy as well as by adherence, intracellular replication, and superoxide anion assays. Both nonopsonized virulent (PPD130/91 and AL9379) and avirulent (PPD125/87 and PPD76/87) bacteria could adhere to and survive and replicate within phagocytes, while only opsonized virulent strains replicated within the phagocytes. Furthermore, only avirulent E. tarda elicited a higher rate of production of reactive oxygen intermediates (ROIs) by phagocytes, indicating that they were unable to avoid and/or resist reactive oxygen radical-based killing by the fish phagocytes. TnphoA transposon mutagenesis was used to construct a library of 200 alkaline phosphatase (PhoA+) fusion mutants from a total of 182,000 transconjugants derived from E. tarda PPD130/91. Five of these mutants induced more ROI production in phagocytes than the wild-type strain. Two mutants had lower replication ability inside phagocytes and moderately higher 50% lethal dose values than the wild-type strain. Sequence analysis revealed that three of these mutants had insertions at sequences having homology to PhoS, dipeptidase, and a surface polymer ligase of lipid A core proteins of other pathogens. These three independent mutations might have changed the cell surface characteristics of the bacteria, which in turn induced phagocytes to produce increased ROIs. Sequences from two other mutants had no homology to known genes, indicating that they may be novel genes for antiphagocytic killing. The present study showed that there are differences in the interactions of virulent and avirulent E. tarda organisms with fish phagocytes and PhoA+ fusion mutants that could be used successfully to identify virulence genes. The information elucidated here would help in the development of suitable strategies to combat the disease caused by E. tarda.

Alkaline Phosphatase↗
PubMed1987

Defects in phagocytic functions.

Phagocytic cells play a critical role in host defence against bacterial infections, often seen as frequent infectious episodes in patients with granulocytopenia, a quantitative phagocytic disorder encountered not infrequently in clinical practice, and in the more rare patients who have a clinically significant qualitative disorder, i.e., a normal number of phagocytes but defects in phagocyte function. In addition to infective agents, phagocytes can be activated by noninfectious structures such as immune complexes. In either case, phagocyte activation, also, inevitably results in destruction of the host's own tissues. Consequently, the degree of phagocyte activity is a double-edged sword: hypoactivity renders the host susceptible to infections while hyperactivity leads to undue phagocyte-mediated tissue injury. This review will discuss the physiology and qualitative defects, including hypoactivity, hyperactivity and inappropriate activation of phagocyte function, as well as the management of the patients.

Bacterial Infections↗
PubMed1982

Interdigitating cells and macrophages in the acute involuting rat thymus. An electron-microscopic study on phagocytic activity and population development.

Phagocytic activity and population development of medullary interdigitating cells (IDC) and cortical macrophages have been studied in the rat thymus after irradiation-induced thymocyte necrosis. IDC clearly demonstrate phagocytic activity particularly in the 16 h stage after irradiation. At this stage the number of necrotic thymocytes is maximal and the total number of phagocytic cells is insufficient to phagocytize all necrotic material. IDC increase in number slightly and are predominantly phagocytizing in the corticomedullary region (CMR), where they appear to develop from macrophage-like cells. The results indicate that medullary IDC can be phagocytic but have a different developmental pathway than cortical macrophages. Cortical macrophages greatly increase in number and acquire the appearance of tingible body macrophages by phagocytizing many necrotic thymocytes. they seem to develop from monocytes that normally enter the thymus at the CMR. During the acute involution macrophages probably also enter the cortex via the connective tissue capsule. It is suggested that thymus medullary IDC probably belong to the mononuclear phagocytes, as do the cortical macrophages. In the specific medullary environment IDC gradually develop their characteristic ultrastructure for an apparently other than phagocytic function. The similarities between IDC and epidermal Langerhans cells are discussed.

Animals↗
PubMed1983

Effect of whole-body irradiation on phagocytic activity of rat alveolar macrophages.

The phagocytic activity of rat alveolar macrophages was studied in vitro for up to six weeks after whole-body gamma irradiation (7.5 Gy). Ingestion of fluorescent latex microspheres was evaluated using both microscopic examination and flow cytometric quantitation. After a transient decrease on first day post-irradiation, a slight increase in the phagocytic ability was observed from day 14 to day 28, with a maximum on day 21. From day 35 onwards, phagocytic capacities returned approximately to those of the controls. The percentage of phagocytic cells (cells having ingested one microsphere or more) increased by 75 per cent on day 21 after irradiation and the phagocytic index (percentage of phagocytic cells X the average number of ingested microspheres per cell) increased by 250 per cent while at the same time, the number of recovered alveolar cells decreased by 37 per cent. The augmentation of phagocytic capacities after irradiation was particularly characterized by an increase in the percentage of cells ingesting more than five microspheres. Flow cytometric studies showed a significant increase in mean cell size on day 21 post-irradiation. The augmentation of the phagocytic activity was not found when macrophages from control rats were incubated with serum or alveolar lavage fluid from an irradiated donor. Augmentation of phagocytic capacity was also observed after 8.5 Gy but no effect could be observed after 6.5 Gy.

Animals↗
PubMed2004

HIV-1 infection does not impair human alveolar macrophage phagocytic function unless combined with cigarette smoking.

OBJECTIVE: Macrophages are an important reservoir for the HIV and contribute to innate lung defense by their ability to phagocytose, digest, and process invading pathogens. We hypothesized that HIV-1 infection may lead to a defect in the phagocytic activity of alveolar macrophages. DESIGN: In order to test this hypothesis, the phagocytic activity of alveolar macrophages from asymptomatic HIV-1 seropositive subjects was compared to healthy seronegative control subjects. Macrophages from one cohort were fed with Escherichia coli and from another cohort with opsonized sheep RBCs (SRBCs), and the phagocytic index was determined at different time intervals. SETTING: A tertiary-care, urban, university-based referral center. PARTICIPANTS: Asymptomatic HIV-1 seropositive subjects and healthy seropositive control subjects recruited from local community. RESULTS: No differences were found in the phagocytic activity between alveolar macrophages from the first cohort of eight seropositive and nine seronegative subjects. Although not statistically significant, there was a trend toward a lower phagocytic activity of HIV-positive smokers compared to HIV-positive nonsmokers. Opsonized phagocytic capacity (using opsonized SRBCs) was further analyzed in a second set of five HIV-positive subjects and five healthy control subjects. Whereas HIV status did not affect opsonized SRBC uptake, a history of smoking was associated with a statistically significant depression in phagocytic index. CONCLUSIONS: Although there is no significant impairment of phagocytic capacity in HIV-positive subjects compared to HIV-negative control subjects, cigarette smoking produces a significant depression in phagocytic activity that is amplified in HIV-positive smokers.

Adult↗
PubMed1992

Influence of involution on intramammary phagocytic defense mechanisms.

Mammary secretions (n = 34 cows) and mammary phagocytes (n = 18 cows) were collected throughout the nonlactating (dry) period to determine changes in intramammary phagocytic defense mechanisms. Mammary secretions were evaluated for their ability to support phagocytosis of Staphylococcus aureus by neutrophils from donor cows and mammary phagocytes for phagocytic and chemiluminescence activity. Ability of secretions to support phagocytosis decreased with advancing length of the dry period. This effect was more pronounced when dry cow secretions constituted 50% of the phagocytic mixture. Phagocytic activity of mammary phagocytes decreased with advancing dry period when autologous secretion was used in the incubation mixture. With homologous secretion, the percentage of phagocytosis increased 5 to 6 d after drying off compared with before drying off and then gradually decreased throughout the remainder of the dry period. Chemiluminescence activity (log10 counts per minute) of mammary phagocytes was lower during the dry period and decreased with advancing dry period. Results indicated diminishing ability of secretions to support phagocytosis and diminished phagocytic and bactericidal mechanisms during the dry period.

Animals↗
PubMed1988

Human phagocytic cell responses to Mycobacterium leprae and Mycobacterium bovis Bacillus Calmette-Guérin. An in vitro comparison of leprosy vaccine components.

Components of current vaccines for Hansen's disease include Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and killed Mycobacterium leprae. BCG infections in humans are rare and most often occur in immune-compromised individuals. M. leprae on the other hand, although not causing clinical disease in most exposed individuals, is capable of infecting and replicating within mononuclear phagocytes. Lymphocytes from patients with the lepromatous form of Hansen's disease exhibit defective lymphokine production when challenged in vitro with M. leprae. This may result in inefficient mononuclear phagocyte activation for oxidative killing. To study the ability of normal phagocytes to ingest and respond oxidatively to BCG and M. leprae, we measured phagocytic cell O2- release and fluorescent oxidative product formation and visually confirmed the ingestion of the organisms. BCG stimulated a vigorous O2- generation in neutrophils and monocytes and flow cytometric oxidative product generation by neutrophils occurred in the majority of cells. M. leprae, stimulated a weak but significant O2- release requiring a high concentration of organisms and long exposure. By flow cytometric analysis, most neutrophils were able to respond to both organisms with the generation of fluorescent oxidative products. Neutrophil oxidative responses to M. leprae were substantially less than responses seen from neutrophils exposed to BCG. By microscopic examination of neutrophils phagocytizing FITC-labeled bacteria, it was shown that both M. leprae and BCG were slowly ingested but that more BCG appeared to be associated with the cell membrane of more of the cells. When phagocytic cells were incubated with BCG and M. leprae for 30 min and subsequently examined by electron microscopy, few organisms were seen in either neutrophils or monocytes. This suggests that BCG are easily recognized and slowly ingested by normal phagocytic cells, the majority of which respond with a strong oxidative burst. M. leprae appeared to only weakly stimulate phagocyte oxidative responses and were also slowly phagocytized.

Adult↗
PubMed1985

[Phagocytic activity of blood leukocytes in calves from birth to 3 months of age].

Forty-three calves of various age from the day of birth to the age of three months were subjected to the 2-hydroxyethylmethacrylate (HEMA) particle phagocytosis test. Significant differences in the phagocytic activity of blood leucocytes were recorded, all depending on age. New-born calves had very low phagocytic activity: only 16.5% of the leucocytes were found to be phagocytic, the phagocytic index being 0.39. A rapid increase in phagocytic activity was recorded during the subsequent days. At the age of three days 43% of the leucocytes of the calves were phagocytic. A decrease in phagocytic activity was found on the sixth to seventh day, and another increase was recorded only from the age of three to four weeks of age. No such changes in the development of phagocytic activity were observed in the calves reared without colostrum administration. Low values were maintained for a longer time after birth without the typical increase on the third to fifth day. Phagocytic activity increased in the zero-colostrum calves experimentally infected with rotavirus.

Age Factors↗
PubMed1993

[Dynamic studies of the leukocyte phagocytic activity after exposure of rats to asbestos and basalt fibers].

The paper presents the results of the dynamic one-year follow-up of the phagocytic activity of Wistar-rats peripheral blood leukocytes following intraperitoneal administration of asbestos and basalt fibres (Man-Made Mineral Fibres--MMMF). We investigated the phagocytic activity of leukocytes in peripheral blood following intraperitoneal administration of asbestos and basalt fibres to rats 2, 24, 48 h as well as 1, 2, 4, 8 weeks and 6 and 12 months after dosing. We investigated the time dependent of the changes of relative granulocytes count, percentage of phagocytizing cells from leukocytes, percentage of phagocytizing granulocytes and percentage of phagocytizing monocytes. The results of our experiment showed that asbestos and basalt fibres differed in their effects on the parameters studied. Granulocyte count as well as the phagocytic activity of leukocytes during the one-year dynamic follow-up in both dust--exposed groups of animals were found to change in two phases, characterised by the initial stimulation of the acute phase (I), followed by the suppression of the parameters in the chronic phase (II). Exposure to asbestos and basalt fibres led, in phase II, to impairment of the phagocytic activity of granulocytes. Asbestos fibres at the same time significantly decreased also the phagocytic activity of monocytes. Exposure to basalt fibres did not affect the phagocytic activity of monocytes in phase II. It follows from the results of the experiment, that the monocytic component of leukocytes probably plays an important role in the development of diseases caused by exposure to fibrous dusts and basalt fibres have smaller biological effects compared with asbestos fibres.

Animals↗
PubMed1975

Phagocytes, lipid-removal and regression of atheroma.

Reticuloendothelial (RE) phagocytes (macrophages and histiocytes) can be distinguished from locally-derived lipid-containing cells (e.g., arterial smooth muscle) or locally derived phagocytes (e.g., Schwann cells and microglia) by the demonstration of a diffuse catalase reaction in a proportion of these RE cells with a short incubation modification of the Novikoff-Golfischer diaminobenzidine histochemical methods. Even though only a proportion of an RE population is catalase-positive, the results accord with the majority of current opinion that most of the cells in atherosclerotic lesions are derived locally, whereas the phagocytes in lipid implants and xanthomas are of RE origin. The phagocytes in the peripheral nerve undergoing Wallerian degeneration appear to be of mixed RE and endogenous origin, whereas microglia around multiple sclerosis plaques seem to be derived locally. Lipid in lesions with RE phagocytes (subcutaneous lipid implants and xanthomas) is relatively rapidly resorbed, whereas lipid in lesions with few RE phagocytes (atherosclerosis) or phagocytes of endogenous origin (CNS degeneration) is more slowly resorbed or partly retained within the tissue. Wallerian degeneration in the peripheral nerve, with its mixed population of RE and endogenous phagocytes, occupies an intermediate position in the speed of lipid removal.

Adult↗