Light and electron microscopic demonstration of D-mannose and D-glucose like sites at the cell surface by means of the lectin from the Lens culinaris

Value of determination of kininase II in bronchoalveolar lavage fluid

Kininase II (KII), identical with angiotensin-I-converting enzyme (E.C. 3.4.15.1) was characterized biochemically and assayed fluorimetrically in bronchoalveolar lavage fluid and serum of 153 patients with several pulmonary disorders. The albumin concentrations of serum and bronchoalveolar lavage fluid (BLF) have also been measured. The pH optimum of KII derived from BLF (LKII) was 8.0. The Michaelis Menten constant was 38.5 mumol/l using benzyloxycarbonyl-phenylalanyl-histidyl-leucine as synthetic substrate. LKII could be inhibited between 80 and 100% by EDTA, phenanthroline, dimercapto-1-propane-sulfonic acid (DMPS), hydroxyquinoline and captopril. The LKII activity (mU/ml BLF) showed no differences in all lung diseases, but the specific LKII (mU/mg albumin) was significantly elevated in sarcoidosis compared to pneumonia (p less than 0.05), fibrosis (p less than 0.05), chronic obstructive bronchitis (p less than 0.005) and lung cancer (p less than 0.01), but not in tuberculosis. This study shows that LKII is measurable in native, unconcentrated BLF and the results indicate that LKII could be useful for diagnosis of pulmonary disorders.

Conjugation of lectins with fluorochromes: an approach to histochemical double labeling of carbohydrate components

Methodical investigations on the coupling of lectins (Con A, LcL, WGA, RcA) to tetramethylrhodamine isothiocyan ate (TRITC) are reported. 20-microgram of TRITC per mg of lectin were found to be the optimal amount of TRITC for the conjugation. With this fluorochrome: protein ratio conjugates were produced which resulted in a specific and brilliant fluorescence in tissue staining. The optimally conjugated lectins were separated on DEAE-Sephadex-A 50. Using two different lectins which were conjugated with TRITC or FITC, respectively, a double labeling of different lectin-binding sites in tissue sections was achieved.

Histochemical lectin affinity technique by means of FITC-labeled serum protein fractions

A two-step affinity technique is described for light microscopic demonstration of the Concanavalin A, Agaricus bisporus lectin and Ricinus communis lectin binding sites by means of various FITC-labeled human and rabbit serum protein fractions. Experiments for the visualization of the Lens culinaris lectin and the Pisum sativum lectin binding sites gaves negative results. The technique consist of two reaction steps which involve the incubation of tissue sections in the lectins followed by the visualization of receptor-bound lectins with FITC-labeled serum protein fractions basing on their carbohydrate content. The specificity of the technique could be demonstrated by the addition of the hapten or by incubation in the FITC-labeled serum protein fractions only. In contrast to the direct or indirect staining methods only very small amounts of purified lectins are necessary.

Electron microscopic demonstration of cell surface carbohydrates by means of peroxidase and ferritin complexes of the Lens culinaris lection

The use of Lens culinaris lectin for electron microscopic detection of D-mannose,- D-glucose and N-acetyl-D-glucosamine like sites on tumor cells, erythrocytes, erythrocyte ghosts, cultured rat liver cells and various tissues of mice is demonstrated. In addition to Lens culinaris lectin-peroxidase reaction (LeL-po reaction) the preparation of active Lens culinaris lectin-ferritin conjugate are described and the specificity of cytochemical reactions are demonstrated. Furthermore experiments by immuno freeze-etching are reported for topological analysis of the lectin receptors.

Electron microscopic demonstration of a saccharide moieties in the hypophase of the alveolar surfactant system

For electron microscopic demonstration of complex carbohydrates and simple sugars in the mouse lung, anionic dye and lectins were used. After immersion fixation of small lung tissue blocks, the alveolar surfactant system was destroyed and only membrane bound carbohydrates (cell coat) could be demonstrated by means of colloidal iron and ruthenium red. Fixation of the whole lung via the visceral pleura preserved the alveolar surfactant system. Only this technique afforded a distinction between cell coat components and hypophase components. After performance of the Concanavalin A-peroxidase technique and after incubation in ferritin-labed Concanavalin A, Lens culinaris lectin or Ricinus communis lectin, various saccharide moieties were demonstrable by immune electron microscopy in the hypophase of the alveolar surfactant system.

Lens culinaris lectin receptors in the plasma membrane of rat liver cells: comparative electron microscopic studies on normal cells, on cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells

The distribution of the Lens culinaris lectin receptors on normal rat liver cells, on rat liver cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells of the rat is investigated by means of the Lens culinaris lectin-peroxidase method and by ferritin conjugated Lens culinaris lectin. The normal rat liver cells show a continuous labeling at the outer membrane surface by the lectin complexes, whereas the transformed rat liver cells exhibit a strong tendency for patchy distribution of the cell surface label. The discontinuous cell surface label in the transformed rat liver cells is obviously caused by an internalization of plasma membrane areas. The importance of these morphological findings in their relationship to Lens culinaris lectin mediated agglutination of rat liver cells and the membrane fluidity in general are discussed. In the experiments no hints to a rotation of the Lens culinaris lectin receptors from the outer membrane surface to the inner membrane surface of rat liver cells can be found.

Interaction of Lens culinaris lectin, concanavalin A, Ricinus communis agglutinin and wheat germ agglutinin with the cell surface of normal and transformed rat liver cells

The observation of BOREK et al. (1973) on nonagglutinability of transformed rat liver cells by Lens culinaris lectin and our ultrastructural findings of a greater mobility of the Lens culinaris lectin receptors on transformed rat liver cells as compared to normal rat liver cells (ROTH 1975) initiated the present agglutination experiments on liver cells with lectins. For agglutination assay the microhemadsorption technique after FURMANSKI et al. (1973) was used with exception of several tests on EDTA-detached cells. The transformed rat liver cells exhibited, in contrast to the findings of BOREK et al. (1973), a positive microhemadsorption with Lens culinaris lectin as well as with Concanavalin A, Ricinus communis lectin and wheat germ agglutinin whereas the normal rat liver cells became positive only after a brief trypsin treatment. The significance of the difference in agglutinability of rat liver cells with Lens culinaris lectin and the other lectins used is discussed with regard to the cell-cell interaction mediated by lectins.

[Studies on the Concanavalin A-receptors of rabbit erythrocytes and of erythyrocyte shadows using immunoelectron microscopy]

The authors report on the immuno electron microscopic demonstration of Concanavalin A-receptors on the erythrocyte membrane. Immuno freeze-etching studies evidenced a focal arrangement of Concanavalin A-receptors on intact erythrocytes as well as on erythrocyte ghosts. Obviously hemolysis by distilled water does not produce changes in the pattern of distribution of Concanavalin A-receptors whereas slight aggregation of plasma membrane intramembraneous particles occured. No unambigous spatial relationship between Concanavalin A-receptors and the plasma membrane intramembraneous particles (intrinsic proteins) of erythrocytes could be observed.

Ultrastructural detection of lectin receptors by cytochemical affinity reaction using mannan-iron complex

A two-step affinity reaction is described for electron microscopic demonstration of the Concanavalin A as well as the Lens culinaris lectin receptors by means of the yeast mannan-iron complex. First the tissue was incubated in the lectin. Afterwards the incubation in the yeast mannan-iron complex was performed and reaction takes place between the still free second sugar binding site of membrane bound lectin molecules and the polysaccharides. This membrane receptor-lectin-polysaccharide complex is revealed by the electron dense iron core of the yeast mannan-iron complex. The specificity of the reactions could be demonstrated by addition of the hapten or by incubation in the yeast mannan-iron complex only. The proposed technique has proved useful for demonstration of lectin receptors in the small intestine.