PubMed Health⌕ Search

Biomedical subjects

T L van Zwet

Publications and source records attributed to T L van Zwet.

9 recordsLinked to original sources
PubMed1979

Hairy-cell leukaemia: a B-lymphocytic disorder.

Fifteen cases of histologically proven hairy-cell leukaemia (HCL) were studied with immunofluorescence, rosette, and phagocytosis techniques. Unfixed hairy cells (HC) bound all kinds of labelled antiserum; but after fixation with formaldehyde a much more selective binding was observed. In two cases no surface-bound Ig was detected; four cases showed gamma and in nine cases two or three heavy chains were found, alpha and delta being the most frequent. Few cases were clearly positive for mu. The picture was invariably monoclonal with respect to light chains. Cytoplasmic Ig was present in only 3/15 cases; it was always IgM. HC did not form E-rosettes or react with a fluorescent anti-T cell antiserum. No EAIgMC-rosettes were formed. All cases showed Fc receptors, which were detected with EAIgG-rosettes (13/13) or with antigen-antibody complexes (6/6). The density of Fc receptors varied widely. Incubation with latex particles resulted in cell-associated particles in 16-63% of the HC; with Staphylococcus epidermidis, the percentage was 2-36. After enzyme treatment (lysostaphin), however, no ingested bacteria were found, which suggests that HC are essentially non-phagocytic. At least 13 cases were therefore classified as B-cell malignancies.

B-Lymphocytes↗
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

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↗
PubMed1976

The morphology of dyserythropoiesis in a patient with acute erythroleukaemia associated with multiple myeloma.

A patient with multiple myeloma in whom acute erythroleukaemia developed 5 years following treatment with irradiation and melphalan is reported. Immunoglobulin synthesis and immunofluorescence investigations provided evidence that the blast cells in the peripheral blood did not belong to the plasma cell series; ultrastructure examination demonstrated their myeloid origin. Chromosomally abnormal cells were observed in both the bone marrow and peripheral blood. Light-and electron microscopy of erythropoiesis in this case showed distinct features of dyserythropoiesis, similar to those described in other entities. The erythroid cell abnormalities are discussed in the light of their being either indications of malignancy or of a reactive process.

Acute Disease↗
PubMed1975

New familial defect in microbicidal function of polymorphonuclear leucocytes.

A family is described in which a defect in intracellular killing affected two, and probably three, siblings of both sexes. From an early age they have had recurrent severe infections. During these episodes their white-blood-cell count became very high. This familial disorder seems to differ from previously reported syndromes of abnormal leucocyte function.

Adolescent↗