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Biomedical subjects

R van Furth

Publications and source records attributed to R van Furth.

At least 325 records · Page 18Linked to original sources
PubMed1979

Phagocytic potential of hairy cells.

The hairy-cells (HC) of 10 patients with hairy-cell leukaemia were studied with several techniques to evaluate their phagocytic potential. Mononuclear cells from normal donors and from patients with acute monocytic leukaemia served as controls. Light microscopically HC seemed to have ingested bacteria or latex particles. Treatment of the cells with lysostaphin, an enzyme that kills extracellular Staphylococcus aureus, showed that almost all 'ingested' bacteria were extracellular. Lanthanum nitrate, added during the fixation procedure for electron microscopy, stained both the outer cell membrane and the membranes of the 'phagosomes' of the HC, also indicating that the 'ingested' particles were extracellular. HC showed no increased oxygen consumption on exposure to bacteria in the presence of serum. Furthermore, HC showed no lysozyme or peroxidase activity, whereas non-specific esterase activity was much weaker than in monocytes. These findings, which show that HC are essentially non-phagocytic, constitute strong evidence against a monocytic origin of the malignant cells of hairy-cell leukaemia.

Colony-Forming Units Assay↗
PubMed1979

In vitro synthesis of humoral factors (immunoglobulins and complement) in lesional skin of leprosy patients.

An in vitro culture technique was used to demonstrate the synthesis of immunoglobulins and complement in lesional skin of patients representing the entire clinico-histopathological spectrum of leprosy. The results indicate that immunoglobulin G is produced in different amounts in the various forms of leprosy. Classification of the patients according to the three main groups shows that a small amount of immunoglobulin G synthesis occurred in tuberculoid leprosy, a distinct amount occurred in borderline leprosy, and large amount occurred in lepromatous leprosy. Contrary to expectation, synthesis of C3 was found only in some of the cultures of these three forms of leprosy. The function of the locally synthesized immunoglobulin G and the findings concerning C3 synthesis are discussed.

Adolescent↗
PubMed1979

Requirement of extracellular complement and immunoglobulin for intracellular killing of micro-organisms by human monocytes.

The role of serum factors in the intracellular killing of bacteria by monocytes was studied on the basis of an assay independent of phagocytosis. After 3 min of phagocytosis of preopsonized bacteria and removal of noningested bacteria, the monocytes containing bacteria are reincubated for various periods and the number of unkilled bacteria is determined by a microbiological method after lysis of the cells. Evidence that this assay measures the killing of ingested bacteria was provided by scanning electron microscopy, lysostaphin treatment, and the effect on the rate of intracellular killing of inactivated serum lacking specific opsonic activity. Intracellular killing of Staphylococcus aureaus, S. epidermidis, and Escherichia coli by human monocytes does not occur or is low in the absence of serum, and maximal killing is only reached when fresh serum is present; intermediate values are obtained in the presence of heat-inactivated serum. These findings indicate that complement stimulates intracellular killing. Isolated heterogeneous immunoglobulin (Ig)G, pFc fragments of heterogeneous IgG, and both IgG1 and IgG3 stimulate intracellular killing of S. aureaus by monocytes to the same degree as heat-inactivated serum. Sphingomyelinase, which decreases the number of Fc receptors, and neuraminidase, which increases these receptors, respectively, decreased and increased the intracellular killing, whereas anti-monocyte serum completely abolished the stimulation of intracellular killing by inactivated serum. These results prove that interaction of the Fc receptor with the Fc part of IgG is required for the intracellular killing. Inhibition of the activation of complement components via the alternative pathway gave a considerable reduction in the intracellular killing of S. aureaus; impairment of the activation via the classical pathway had no effect. The addition of complement components to heat-inactivated serum showed that intracellular killing is maximal only when C3b is generated. Reduction of the number of C3b receptors in the membrane by trypsin or pronase decreased intracellular killing in the presence of fresh serum; anti-monocyte serum completely abolished the stimulation of intracellular killing by fresh serum. These results lead to the conclusion that intracellular killing is also dependent on the interaction between C3b and its receptor in the membrane.

Blood Bactericidal Activity↗
PubMed1979

Kinetics of phagocytosis of Staphylococcus aureus and Escherichia coli by human granulocytes.

Although phagocytosis of micro-organisms by granulocytes is one of the most important defence mechanisms against infection, little is known about the kinetics of this process. The present study showed that the rate of ingestion of Staphylococcus aureus and Escherichia coli depends on the concentrations of the granulocytes and bacteria. Phagocytosis of bacteria at a bacteria-to-cell ratio in the range between 100:1 and 1:10 showed an exponential course during the first 30 min. At a bacteria-to-cell ratio of 1:1, application of a correction for the outgrowth of extracellular bacteria gave an exponential course of ingestion over the first 90-min period. Since it was found that the phagocytosis of bacteria by granulocytes at various bacteria-to-cell ratios can be described with Michaelis-Menten kinetics, we studied the kinetics of phagocytosis on the basis of the initial rate for the first 30-min period. The rate of phagocytosis and the maximal degree of ingestion of bacteria by granulocytes proved to be related to the concentration of serum used in the assay. The minimal serum concentration required for maximal ingestion was 2.5% for Staphylococcus aureus and 5% for Escherichia coli. When bacteria were pre-opsonized, the duration of pre-opsonization proved to be limiting for the rate of phagocytosis in dependence on the serum concentration. The effect of temperature on the phagocytosis of micro-organisms proved to be two-fold. First, at temperatures between 4 and 33 degrees a decrease in the functioning of the cells leads to a decrease in the rate of phagocytosis. Above 42 degrees, the temperature affects mainly the opsonization of the micro-organisms and has only a slight influence on the ingestion process. From the data obtained in this study, maximal rates of 6.3 X 10(6) Staphylococcus aureus/5 X 10(6) granulocytes/min and of 7.1 X 10(6) Escherichia coli/5 X 10(6) granulocytes/min were calculated for phagocytosis at a bacteria-to-cell ratio of 100:1 at 37 degrees, i.e. on average about one bacterium per granulocyte per min. The maximum calculated number of bacteria ingested by one granulocyte lies between 40 and 50.

Blood↗
PubMed1979

Characteristics of human mononuclear phagocytes.

In this study human mononuclear phagocytes from the bone marrow (promonocytes and monocytes), peripheral blood monocytes, and tissue macrophages from the skin and the peritoneal cavity were studied with respect to their morphological, cytochemical, and functional characteristics, cell surface receptors, and 3H-thymidine incorporation in vitro. The results show similarities between mononuclear phagocytes of the three body compartments with respect to esterase staining, the presence of peroxidase-positive granules, the presence of IgG and C receptors, and pinocytic and phagocytic activity. Promonocytes are the most immature mononuclear phagocytes identified in human bone marrow, and since about 80% of these cells incorporate 3H-thymidine, they are actively dividing cells. Monocytes, whether in bone marrow or the peripheral blood, and both skin and peritoneal macrophages label minimally with 3H-thymidine and thus are nondividing cells. Since the characteristics of mononuclear phagocytes in man and mouse do not diverge greatly, it is probable that the cell sequence based on in vitro and in vivo 3H-thymidine labeling studies in the mouse holds for man as well. The successive stages of development of the human mononuclear phagocyte cell line will then be as follows: monoblasts (not yet characterized in man) divide to form promonocytes, and these cells in turn divide and give rise to monocytes that do not divide further; they leave the bone marrow, circulate in the peripheral blood, and finally become macrophages in the various tissues.

Ascitic Fluid↗
PubMed1978

The origin, kinetics, and characteristics of the Kupffer cells in the normal steady state.

Enzymatic digestion with pronase and DNAase was used to isolate Kupffer cells from mouse liver. The characteristics of these cells were found to be similar to those of peritoneal macrophages, except that in the initial suspension the percentage of Kupffer cells with Fc receptors was low, C receptors were absent and the ingestion of opsenized bacteria was very poor, because of the effect of pronase on the cell membrane. After 24 h incubation in vitro all these characteristics return. The in vitro and 1 h-pulse [(3)H]thymidine labeling of the Kupffer cells is low (0.8 and 1 percent, respectively) indicating that in essence these cells do not divide. It was also shown that the small percentage of in vitro labeled Kupffer cells was recently derived from the circulation. After an intravenous injection of zymosan the in vitro labeling index of the Kupffer cells increased 16-fold, but it was proven that these dividing cells were immature mononuclear phagocytes very recently recruited from the bone marrow. The labeling of Kupffer cells aider one or four injections of [(3)H]thymidine reached a peak of 10.4 percent at 48 h or 24.1 percent at 60 h, respectively, indicating that these cells are derived from labeled monocytes. Further evidence for this conclusion was obtained by the absence of an increase of labeled Kupffer cells during treatment with hydrocortisone, which causes a monocytopenia during which no circulating monocytes are available to migrate to the tissues. Labeling studies in animals X-irradiated with hind-limb shielding gave a Kupffer cell labeling index of 5-10 percent of the normal values, which confirms their bone marrow origin. A quantitative study on the production of labeled monocytes in the bone marrow and their transit through the circulation showed that in the normal steady state at least 56.4 percent of the monocytes leaving the circulation become Kupffer cells. Considering the Kupffer cells as kinetically homogeneous this gives a mean turnover time of the total population of Kupffer cells of 21 days.

Animals↗
PubMed1978

Culture of mononuclear phagocytes on a teflon surface to prevent adherence.

A method is described for the culture of mononuclear phagocytes in suspension by incubation on a Teflon film to which the cells do not adhere. The characteristics of peritoneal macrophages, bone marrow mononuclear phagocytes, macrophage cell lines, and fibroblasts cultured in this way are similar to those observed after culture on glass or plastic surfaces. Culture of mononuclear phagocytes in Teflon film dishes has three important advantages: the cells can be easily harvested without damage, recovery is almost complete, and the cells are not functionally impaired. Thus, this method makes it possible to use cultured mononuclear phagocytes for many studied that could previously only be done in freshly collected cells.

Cell Adhesion↗
PubMed1977

Cell kinetics during inflammation.

This communication deals with the production and kinetics of mononuclear phagocytes and polymorphonuclear phagocytes in the normal steady state and during an acute inflammatory reaction and with the humoral regulation of the increased production of leucocytes during an inflammatory reaction. The effect of hydrocortisone and azathioprine on both kinds of phagocytic cells is also discussed.

Acute Disease↗
PubMed1977

Kinetics of phagocytosis and intracellular killing of Candida albicans by human granulocytes and monocytes.

The study of the phagocytosis and intracellular killing of Candida albicans by granulocytes and monocytes has been hampered by the budding and pseudomycelium formation of this yeast during a relatively short incubation period at 37 degrees C and by the similar density of candida cells and phagocytes, which makes differential centrifugation impossible. In the present study, C. albicans was used after 5 days of preculture at 30 degrees C, after which the number of candida cells remained constant during incubation at 37 degrees C for 90 min. On this basis, phagocytosis and intracellular killing were limited to a period of 60 min. Phagocytosis of C. albicans by granulocytes and monocytes was measured with a hemocytometer, the number of extracellular candida being a measure of the ingestion of these microorganisms. After 60 min, 96% of the candida cells were ingested by normal human granulocytes and monocytes. This process was dependent on the opsonin concentration and temperature and was inhibited by mono-iodoacetic acid. Heat-inactivated serum was less active than fresh serum, reflecting the role of complement factors with respect to opsonization. Intracellular killing was measured by a microbiological assay. After 60 min of incubation of phagocytes together with C. albicans and serum, human granulocytes and monocytes killed 58 and 50% of the ingested candida, respectively. This process was inhibited by phenylbutazone. Phagocytes from patients with chronic granulomatous disease showed impaired intracellular killing.

Candida albicans↗