Publisher Summary Lectins play an important role in the development of immunology. Lectins also find application in serological laboratories for typing blood and determining secretor status, separating leucocytes from erythrocytes, and agglutinating cells from blood in the preparation of plasma. They serve as reagents for the detection, isolation, and characterization of carbohydrate-containing macromolecules, including blood-group antigens. In their interaction with saccharides, lectins serve as models for carbohydrate-specific antibodies, with the important advantage to purify lectins in gram quantities. Lectins are classified according to their carbohydrate-binding specificity that includes D-mannose(D-glucose)-binding lectins and 2-acetamido-2-deoxy-D-glucose-binding lectins. The chapter considers only those lectins that have been purified to homogeneity, and studied with regard to their biophysical, biochemical, and carbohydrate-binding specificity. The chapter also describes the cell-binding and biological properties of lectins. The chapter concludes with the description of several glycopeptide structures showing the carbohydrate-binding loci with which various lectins interact.

The lectins : carbohydrate-binding proteins of plants and animals

A comparative study of glycoproteins from the surface of control and Rous sarcoma virus transformed hamster cells.

Publisher Summary There are two types of surface layers associated with the periphery of animal cells: (1) cell coats, located on the outer surface of most types of cells and (2) basal and external laminas, which border the surface of epithelial and mesenchymal cells, respectively. Both these types of surface layers differ in fine structure, tinctorial affinities, topographical relation to the plasma membrane, and in chemical composition. Cell coats are present in a large variety of animal cells as carbohydrate-containing components of the cell membrane. In some cells, surface coats occur as peripheral sugar moieties of glycoproteins integrated in the plasma membrane and in other cells, they form a thin coat of mucopolysaccharide or glycoprotein material attached to the outer leaflet of the lipoprotein plasma membrane. The intimal relation of cell coats with the plasma membrane, their resistance to physical treatments, and their relation to specific cell types show that they are not merely inert films of condensed ground substance or mucus but integral components of the cell membrane responsible for some of the fundamental properties of the cell surface.

The Surface Coats of Animal Cells

Publisher Summary This chapter focuses on the degree of involvement of immune mechanisms in modifying tumor formation and growth during chemical carcinogenesis. During the past two decades, the concept that tumors express antigens against which the host is capable of evoking an immune response has been firmly established. The validity of these studies, as well as comparable findings with MC-induced rat sarcomas (Baldwin, 1955), was critically analyzed by Prehn and Main (1957) who conclusively showed that the induction of immunity to transplanted sarcoma grafts was a tumor-specific phenomenon because immunized mice could still accept skin grafts from the tumor donor, precluding the involvement of an alloantigenic immune response. Evidence shows that tumor rejection antigens are specific and permanent, or quasi-permanent, characteristics of cells transformed by chemical carcinogens. Chemically induced tumors also express antigens normally present in embryonic, but not adult, tissue that may be viewed as the products of dedifferentiation processes induced by the carcinogen, and concurrently there is frequently a deletion of normal tissue antigens. The immunological responses to neoantigens expressed on preneoplastic and neoplastic cells can influence, either positively or negatively, the course of chemical carcinogenesis.

Immunological aspects of chemical carcinogenesis.

The Analysis of Dietary Fiber

Summary Sialic acid has been shown to contribute significantly to the cell-surface charge of tumor cells. In order to elucidate the chemical nature of the sialic acid-containing molecules present on the tumor cell surface, a procedure for the isolation of a sialoglycopeptide fraction from the surface of Novikoff ascites cells has been developed. Digestion of tumor cell suspensions with papain liberates a sialoglycopeptide fraction from the cell surface. This fraction was partially purified using trichloroacetic acid precipitation, dialysis, and gel filtration on Sephadex G-50. The sialoglycopeptide fraction contains 65–80% of the neuraminidase-labile sialic acid present on the surface of these cells. Quantitative analysis of the composition of this fraction revealed the presence of the following monosaccharides, expressed per mg glycopeptide: 0.39 µmole sialic acid, 0.41 µmole glucosamine, 0.23 µmole galactosamine, 0.15 µmole mannose, 0.54 µmole galactose, 0.53 µmole glucose, and 0.15 µmole uronic acid. Amino acid analysis indicated a peptide content of 15%. Amino acids present in the highest amounts were threonine, aspartic acid, glutamic acid, serine, proline, alanine, and valine (molar ratio, 4:2:1.5:1:1:1:1).

https://cancerres.aacrjournals.org/content/canres/29/11/2034.full.pdf

Roberta S. Lantz

Papers

Isolation and Chemical Characterization of a Cell-Surface Sialoglycopeptide Fraction from Novikoff Ascites Cells

Separation and quantitation of saccharides by ion-exchange chromatography utilizing boric acid-glycerol buffers.