The binding of lectins to components of plasma membranes from porcine submaxillary lymph node lymphocytes

Acriflavine-Induced Surface Changes in Three Tumor Cell Types and Differential Sensitivity to Lectins

Phytohemagglutinin (PHA) and concanavalin A (Con A) were used as probes to detect changes in the cell surface of Dalton's lymphoma, sarcoma-180 and Ehrlich's carcinoma after short in vitro exposure to acriflavine. Dye-treated cells showed enhancement of agglutination both by PHA and Con A, and such enhancement was found to be dependent on the time of exposure and concentration of acriflavine. However, PHA-induced percent agglutination seemed to be much higher than that of Con A among the 3 cell types. There were also marked differences among the 3 cell types in order of their sensitivity to lectin-mediated agglutination. The strength of the response was greater in lymphoma to both PHA and Con A than that of sarcoma-180 and carcinoma cells, which appeared to be most resistant. Acriflavine, which is known as an intercalative agent with DNA, induces cell surface changes by promoting lectin-mediated cellular agglutination.

B lymphocytes respond specifically to phytohaemagglutinin after liposome-dependent transfer of purified phytohaemagglutinin receptors

Phytohaemagglutinin (PHA) receptor glycoproteins purified by affinity chromatography from porcine splenic lymphocytes, were reconstituted into vesicles made of phosphatidylcholine and phosphatidylserine, concomitantly with Sendai virus fusogenic proteins HN and F. The vesicles were used as a vehicle to insert the PHA receptor glycoproteins into a highly enriched population of porcine B lymphocytes. Fluorescence analyses showed that 52 +/- 2% of the reconstituted B cells had incorporated the lectin receptors. The modified B lymphocytes were assayed for their response (tritiated thymidine incorporation into nucleic acids) to PHA, concanavalin A (Con A), or to lipopolysaccharide (LPS). The results showed that porcine B cells fused with vesicles containing only viral fusogenic proteins failed to respond to either PHA or Con A. Tritiated thymidine incorporation was similar to background values. The cells did, however, respond to LPS with values of label incorporation similar to those observed in the case of pre-fused B lymphocytes. When purified B lymphocytes were fused with vesicles containing PHA receptors and viral fusogenic proteins, assays of thymidine incorporation showed a statistically significant (P less than 0.001) and specific response of the modified cells to PHA stimulation. Reconstituted cells cultured in the presence of PHA incorporated approximately nine times more radioactive label than pre-fused cells or cells fused with vesicles containing only fusogenic viral proteins. In marked contrast, reconstituted B lymphocytes did not show any significant label incorporation above background level in response to Con A, but they retained their ability to respond to LPS. Our findings suggest that B lymphocytes can be made to respond specifically to PHA by insertion of appropriate lymphocyte-derived receptors.

Functional domains of the T lymphocyte plasma membrane: characterization of the polypeptide composition

Highly purified plasma membranes from calf thymocytes were fractionated by affinity chromatography on Concanavalin A-Sepharose into two subfractions, one eluting freely from the affinity column (MF1) and a second being specifically retained (MF2). SDS-polyacrylamide-gel-electrophoresis revealed different polypeptide patterns of the two plasma membrane subfractions. Polypeptides of apparent molecular weights of 170, 150, 110, 94, 39, and 30 kDa were several-fold enriched in the adherent fraction, MF2. In contrast, several proteins in the 55-65 kDa range were preferentially recovered in the non-adherent fraction. Five Five of the six polypeptides, preferentially recovered in MF2 proved to be glycoproteins, the 39 kDa peptide was non-glycosilated. The differences in the amounts of the polypeptides specifically enriched in the adherent fraction MF2 became even more clear-cut when plasma membranes solubilized with non-ionic detergents (lysolecithin, ET-18-2H, Triton-X-100) were separated by affinity chromatography on Concanavalin A-Sepharose. The non-glycosilated peptide of apparent molecular weight of 39 kDa was recovered together with several glycoproteins in the adherent fraction, MF2, suggesting that not single glycoproteins, but plasma membrane domains were separated by Concanavalin A-Sepharose. Although the glycoproteins of the non-adherent fraction MF1 bound significant amounts of Concanavalin A, the major Concanavalin A binding glycoproteins were recovered in the adherent fraction, MF2. The plasma membrane subfractions showed also different functional properties, the specific activities [Na+ + K+]AT-Pase, Ca2+ ATPase and lysolecithin acyltransferase were several-fold enriched in the adherent fraction, MF2, as compared to MF1. The data suggest the existence of plasma membrane domains in the plasma membranes of thymocytes consisting of a different set of proteins, among others the major Concanavalin A binding glycoproteins with some membrane bound enzymes, probably implicated in the initiation of lymphocyte activation.

Separation of human lymphocyte subclasses by rosettes with latex-lectin particles

The specificity and affinity of eight lectins (concanavalin A, L. culinaris, P. sativum, phytohemagglutinin P, D. biflorus, soybean agglutinin, T. purpureus, and T. vulgaris) to B, T, T gamma, and T mu lymphocytes from the blood of normal subjects were determined. Lectins attached to latex particles were used to evaluate the binding of each lectin to individual cells. The rosette percentage found in each lymphocyte population expresses the specificity index and the specific sugar concentrations needed to decrease the rosette percentage by 50% is taken as the affinity index. B Lymphocytes showed a major subclass, with respect to T lymphocytes, with receptors for WGA, SBA, D. biflorus, L. culinaris, and P. sativum lectins. In contrast, T lymphocytes exhibit a greater number of cells with specific receptors for Con A, T. purpureus, and PHA lectins than B lymphocytes, the T gamma subpopulation being responsible for the specificity of the first two lectins and the T mu subpopulation for the PHA lectin.

Interaction of monomeric and oligomeric soybean agglutinins with pig lymphocytes and plasma membranes

The pig lymphocyte surface contains two distinct receptor classes for monomeric (nonmitogen) and oligomeric (mitogen) soybean agglutinins. The major class (70-80%) for which both forms compete effectively binds them with a similar weak avidity in a non-cooperative monovalent reaction. This class appears to be one or more plasma membrane glycolipids and not involved in the mitogenic process. The minor class (20-30%) binds the monomer weakly and non-cooperatively. It binds the oligomers strongly via positively cooperative interactions involving mobile surface molecules in a metabolically energy-independent clustering process. The minor class appears to be one or more of seven plasma-membrane glycopolypeptides. The monomer does not compete effectively for this class nor does it specifically inhibit the mitogenicity of the oligomers, suggesting that receptors involved in the mitogenic process fall into the minor class and are likely to be glycopolypeptides.

Separation and localization on sodium dodecyl sulfate polyacrylamide gels of pig spleen lymphocyte plasma membrane proteins which bind 125I-labelled phytohemagglutinin

The protein constituents of splenic pig lymphocytes derived from the plasma membranes, the endoplasmic reticulum or from a non-ionic (Nonidet P-40) detergent of whole cells have been separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, under reducing and non-reducing conditions. The binding of Phaseolus vulgaris (red kidney bean) phytohemagglutinin to these constituents has been studied by incubation of the labelled lectin with the undried electrophoretograms. Results show characteristic phytohemagglutinin-reactive components in each cell fraction, although the majority of the lectin-binding bands are common to the three fractions. Comparison of binding patterns for the reduced and non-reduced electrophoretograms does not reveal significant differences between the binding profiles. The components which bind the lectin in the largest amounts are located in the upper halves of the gels, which correspond to a molecular range of (75-250) . 10(3) daltons. Our data suggest that pig spleen lymphocyte plasma membranes contain at least 25-30 glycoproteins which can bind phytohemagglutinin. Iodine-labelled phytohemagglutinin binds to the vesicles prepared from lymphocyte plasma membranes and the Scatchard plot shows a non-linear upward concave curve.

The lectin binding sites on the membranes of the nuclear envelope, mitochondria and the cell surface of human lymphoblastoid cells

The membranes of the cell surface, the endoplasmic reticulum, outer and inner mitochondrial leaflet and nuclear envelope were isolated from three human lymphoblastoid cell lines. Membrane components were separated by dodecyl sulfate polyacrylamide gel electrophoresis and the gels incubated with the radioiodinated lectins from lentil, castor bean, scarlet runner bean, gorse seed and Roman snail. After gel slicing and counting, the molecular weights of the lectin binding sites were determined. About 20 glycoproteins were identified as constituents of the plasma membrane, a similar glycoprotein distribution was observed in the endoplasmic reticulum. The outer mitochondrial membrane contained some impurities from the plasma membrane, the inner mitochondrial membrane lacked specific lectin receptors. Two prominent glycoproteins with molecular weights of 70 000 and 60 000 were identified with the castor bean lectin in the nuclear envelope.