Heterogeneity of concanavalin A binding by mouse peritoneal macrophages

Lectin binding pattern of Schwann cells and macrophages in 2,5-hexanedione-induced axonal degeneration in rats

The lectin binding pattern of both Schwann cells and macrophages has been studied during axonal degeneration induced in the rat sciatic nerve by chronic administration of 2,5-hexanedione (0.8 ml/kg per day i.p. for 20 days). In particular, the present study aimed to establish a possible relationship between macrophage activation and expression of lectin binding sites. To identify and distinguish between Schwann cells and macrophages, electron microscopy was combined with the lectin staining method. On 2,5-hexanedione injury, a drastic disorganization of both axon and myelin sheath occurred and nerve fibers were replaced by a chain of ovoids. Besides the well-established concept that Schwann cells and macrophages cooperate in the removal of the myelin debris during axonal degeneration, evidence is presented that expression of binding sites to lectins is closely related to macrophage activation. Monocytes occasionally present in control nerves were labelled only by Con A and sialidase-peanut sequence; in 2,5-hexanedione degeneration monocytes, prephagocytes (macrophages with minute bubbles) and phagocytes (macrophages with large bubbles) were labelled also by peanut, wheat germ and BSA I-B4; moreover, phagocytes were labelled by soybean as well, thus showing a clearly differentiation-dependent binding pattern. Since changes in lectin binding pattern may reflect changes in complex carbohydrate structures, the results show that the expression of certain glycoproteins may be closely related to activation of macrophages in response to toxic injuries.

Immunocytochemical demonstration of wheat germ agglutinin (WGA)-receptors on the cell surface of guinea pig peritoneal macrophages

WGA-receptors on the surface of resident guinea pig peritoneal macrophages were investigated. Macrophages were characterized by the endogenous peroxidase pattern. Two different immunogold techniques, the indirect WGA-anti WGA-protein A-gold technique and the direct WGA/BSA-gold technique were compared to evaluate their suitability for quantification of WGA binding sites on the cell surface. Because of the higher binding specificity the direct technique should be preferred for quantitative studies.

In vivo changes of heterogeneity of mouse peritoneal macrophages induced by cis-diamminedichloroplatinum (II) (cis-DDP) and related platinum compounds

The s.c. injection of cis-DDP into ABD2F1 mice (8 mg/kg b.m.) resulted in alterations of size and surface structure of peritoneal macrophages (PM) and in a reduction of the mean number of Concanavalin A (ConA) binding sites of PM. The PM population of control mice which received physiological saline only consisted of 2 subgroups with a higher and a lower mean ConA binding site number per cell. Contrarily, PM of cis-DDP-treated mice failed the subpopulation with higher ConA binding site number. A loss of this subpopulation was also found in mice treated with platinum salt K2PtCl4 or K2PtCl6. X-ray microanalytically determined elemental contents of PM of control and treated mice showed a correlation between ConA binding site number and cellular concentration of phosphorus or sulphur with the exception of a small group of PM which was characterized by a high content of sulphur and a low number of ConA binding site. This correlation was not found in normal mice.

Nonimmune-mediated phagocytosis by "premedullary" lung macrophages: effects of concanavalin A, tuftsin, and macrophage-inhibitory peptide

Free cells arising in organ-cultured embryonic rat and hamster lungs share ultrastructural, lysosomal enzyme, and cell membrane properties with typical alveolar macrophages, expressing the developmental potential of the earliest-macrophage precursors resident in the lungs. In the lung culture environment cell proliferation is supported and macrophage attributes are developed despite absence of lymphocytes from the system. We have shown previously that among these attributes, the cells respond with increased phagocytosis of erythrocytes if these are opsonized with immunoglobulin G. Attention has now been turned to the question of nonimmune-mediated phagocytosis by the same population. Living macrophages that emerged from lung cultures bound rhodamine-coupled soybean and wheat germ agglutinins to a greater degree than concanavalin A (Con A), which nevertheless promoted lateral translocation of occupied receptors in the cell membrane. Emerged cells also phagocytosed living bacteria and native yeast cells (Y). The percentage of macrophages ingesting 3 or more yeast cells increased 400 (hamsters) to 500% (rats) when yeast was preincubated with Con A (200 micrograms/ml). Pretreatment of macrophages with Tuftsin (100 microM) enhanced uptake of Y by 100 (hamster) to 200% (rat). Pretreatment of macrophages with macrophage-inhibitory peptide (500 microM) appeared to inhibit phagocytosis of Y by 60% in hamsters but had no significant effect on cells from rat lung cultures.

The cell surface coat in neurulating mouse and rat embryos, studied with lectins

Carbohydrates in the surface coat of cells are thought to have a function in cell adhesion. The surface coat of cells, located in the fusion zone of the neural walls is investigated during neural tube closure in mammalian embryos. The presence of alpha-D-mannose, alpha-D-glucose and N-acetyl-D-glucosamine is quantified with the help of the lectins concanavalin A and wheat germ agglutinin in absence or after enzymic treatment. A two-step incubation is used, in which the second step consists of a protein-gold conjugate. A high incidence of these sugar residues was found in the fusion zone, indicating a relation to the specific capacity of these cells in establishing cell contacts.

Lectin binding and surface glycoprotein pattern of human macrophage populations

In the present study unstimulated and stimulated human blood monocytes, untreated and phorbol ester treated U-937 cells, as well as human peritoneal and alveolar macrophages were studied with respect to their surface membrane properties. Binding of different lectins and electrophoretic patterns of tritium labeled surface glycoproteins were compared. The analysis of surface glycoproteins could be interpreted as evidence for a common origin of the analysed cell populations. Furthermore, banding patterns of glycoproteins might be useful to define certain activation states within monocyte/macrophage differentiation. In contrast, lectin binding pattern did not clearly discriminate macrophage subpopulations.

Binding of concanavalin A and wheat germ agglutinin by murine peritoneal macrophages: Ultrastructural and cytophotometric studies

Concanavalin A and wheat germ agglutinin were employed in conjunction with the horseradish peroxidase-diaminobenzidine method for the detection of sugar residues on the surface coat of exudate and resident murine peritoneal macrophages. Electron microscopical and cytophotometric techniques were used for the visualization and quantification of the final reaction product on the surface of cells. After incubation with concanavalin A and wheat germ agglutinin, both exudate and resident macrophages showed readily detectable final reaction product indicating the presence of numerous, easily accessible, alpha-methyl-D-mannosyl and N-acetyl-D-glucosaminyl residues on their surface. The binding of concanavalin A was higher with resident than with exudate macrophages. With wheat germ agglutinin, a different pattern of lectin binding was observed: more electron-dense product was deposited on exudate than on resident macrophage surfaces. The binding of concanavalin A and wheat germ agglutinin to macrophages was inhibited by the competing sugars alpha-methyl-D-mannoside and N-acetyl-D-glucosamine, respectively.

Wheat-germ agglutinin binding in four types of mouse peritoneal macrophage

After stimulation of the mouse peritoneal cavity with newborn calf serum (NBCS), four types of monocyte and macrophage were distinguished on the basis of peroxidase (PO) patterns. These cell types showed heterogeneity in their binding of the lectin wheat-germ agglutinin (WGA). At 16 h after stimulation, monocytes and monocyte-derived macrophages (with PO activity in granules) had a high level of WGA binding; PO-negative macrophages showed moderate WGA binding, and resident macrophages (with PO activity in the RER and nuclear envelope) had low WGA binding. At later time-points after stimulation, each of these cell types lost WGA binding sites. This decrease was related to a process of differentiation and to a modulation, affected by environmental factors. The present results also indicated that PO-negative macrophages can give rise to resident macrophages. Whether these PO-negative cells are monocyte derived or originate otherwise needs further investigation. The fourth type of macrophage, the exudate-resident cell (with PO activity both in granules and in the RER and nuclear envelope), with a WGA binding pattern similar to that of monocytes and monocyte-derived macrophages, was considered not to be a resident precursor cell.

Autoradiographical demonstration of C3b receptor activity on resident peritoneal macrophages

The present study was performed to evaluate the usefulness of 125I-labelled C3b bound to constituents of sheep erythrocyte membranes (125I-C3b-OR) for the demonstration of C3b receptor activity of resident peritoneal macrophages at the electron-microscopical level. The binding of 125I-C3b-OR to the cells was studied in biochemical and autoradiographical experiments. The amount of cell-associated radioactivity was dependent on the presence of unlabelled aggregated C3b (AC3b) in a dose-response manner, and diminished strongly after functional inactivation of the receptor by trypsin treatment. In addition, it was found that at 4 degrees C most of the label was associated with the cell surface. However, when the incubation temperature was raised from 4 degrees C to 37 degrees C, internalization of the label was observed. These results indicate that 125I-C3b-OR is a suitable agent for further characterization of the C3b receptor-function of resident peritoneal macrophages at the electron-microscopical level.