Interaction of lectins with human T lymphocytes mitogenic properties, inhibitory effects, binding to the cell membrane and to isolated surface glycopeptides

Abstract

The mode of interaction of twelve lectins with human T lymphocytes was investigated. In order to establish possible differences between mitogenic and nonmitogenic lectins, they were studied for their capacity to induce or inhibit DNA synthesis. Their interaction with intact T cells was studied by immunofluorescence and "Cr release. Further, lectins conjugated to Sepharose were investigated with regard to their capacity to bind surface glycopeptides from T cell lysates. Operationally, the lectins could be divided into three groups: (a) mitogenic lectins; (b) lectins inhibitory for lymphocyte mitogenesis as induced by leucoagglutinin (La) from Phaseolus vulgaris; and (c) nonmitogenic lectins which were noninhibitory in this La system. Six lectins were nonmitogenic. For two or possibly three of these, lack of mitogenicity was due to complete or partial failure to bind to the lymphocytes. This explanation could not account for lack of mitogenicity of the other three nonmitogenic lectins. Only two of the lectins utilized inhibited La-induced mitogenesis. However, when the lectins were compared with regard to their capacity to bind surface glycopeptides from T cell lysates, important differences between mitogenic and nonmitogenic lectins were seen. As revealed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate and autoradiography, the mitogenic lectins bound a larger number of surface glycopeptides (15-20) than the nonmitogenic lectins (3-10). More importantly, five distinct glycopeptides (gp 135 K, 125 K, 105 K, 95 K and 43 K) were bound by all mitogenic lectins but not by the nonmitogenic lectins. It remains to be established whether these glycopeptides are present on the T cells which are susceptible to the mitogenic action of the lectins and whether it is the interaction of the lectins with one or several of them which triggers mitogenicity.

T-lymphocyte heterogeneity: wheat germ agglutinin labeling of transmembrane glycoproteins.

“…Conceivably, but in our opinion less likely, individual differences in labeling might also result from differences in the association of the transmembrane proteins with putative components ofthe membrane skeleton, resulting in differential partition on fracture. In either case, heterogeneity of T-cell populations, as revealed by fracture-labeling, retains possible operational value and a significance that is reinforced by the homogeneous labeling patterns so far observed in other cells and by the recent finding of multiple WGA-binding glycoproteins in the plasma membranes of human T cells (19). The effect ofWGA (stimulatory/inhibitory; see refs.…”

“…At present, opportunities for correlation of the pattern of WGA labeling of P faces, as reported here, with available data on T-lymphocyte plasma membrane glycoproteins are limited. In thymus-derived lymphocytes, most plasma membrane glycoproteins appear to contain terminal sialic acid residues on their oligosaccharide chains (6,19). WGA recognizes and binds to sialic acid, although it can also bind to GlcNAc residues deeper in the oligosaccharide chains that are revealed after removal of the terminal sialic acid by neuraminidase (20).…”

Binding specificities of the lectins from Helix pomatia, soybean and peanut against different glycosphingolipids in liposome membranes

“…Little is known about the cell surface carbohydrate structures involved in the binding to these 3 lectins [6,7]. To elucidate the possible role of sialic acid as a modulator of ,8-linked terminal, non-reducing D-galactose and Nacetyl-D-galactosamine, we have studied the SBA, PNA and HPA binding of the gangliosides GM2, GM1 and GDla, and the corresponding desialylated glycosphingolipids GA2 and GA1 .…”

Mitogenic leukoagglutinin from Phaseolus vulgaris binds to a pentasaccharide unit in N-acetyllactosamine-type glycoprotein glycans.

“…The subunits are of two different types, designated leukocyte reactive (L) and erythrocyte reactive (E), and occur in the combinations L4, L3E, L2E2, LE3, and E4 (1)(2)(3). L has high affinity for lymphocyte surface receptors (1)(2)(3)(4)(5) but little for those of erythrocytes (refs. 1 and 2; unpublished data) and is responsible for the mitogenic properties of the isolectins (1)(2)(3)(4)(5).…”

“…L has high affinity for lymphocyte surface receptors (1)(2)(3)(4)(5) but little for those of erythrocytes (refs. 1 and 2; unpublished data) and is responsible for the mitogenic properties of the isolectins (1)(2)(3)(4)(5). E is responsible for the erythrocyte agglutinating properties (3,6).…”